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For better players, the toughest shot is the Lowest lofted club off the ground. 3w off the deck for example.  Tour players especially, hit their 2nd shots into par 5s the least often with a low lofted wood.  Trying to hit it high and far they tend to Tilt back and drop kick them where if it were less less lofted, like a driver on a tee, it wouldn't be so hard, because it's on a tee and not off the ground so you have some room for the low point to be before the ball and hit with an upward aoa.  When the ball is on the ground, the low point has to be past the ball otherwise you'll hit it thin or fat . 
Sung Kang comes to mind 
https://fb.watch/mvn_WD0KG-/?mibextid=mXAvQF
 

Highly recommend the Stack & Tilt camp at the JW Marriott in Aventura FL.  2:1 student teacher ratio.  Very educational.  
https://stackandtilt.com/events/stack-tilt-camp-usa-miami-3/
 

Measuring putter shafts has become one of my most fascinating research items to date.  Reading some of the commentary here I appreciate everyone's desire (psychosis 🙃) in improving tech. 
There are only 2 machines designed to measure the shaft in time and space during a swing/stroke - GEARs being the one I have, and fuji's enso the other.  I've worked with multiple manufacturers as well as client testing putters where we look at their favorite gamer club, and compare it to their most hated gamer club. In that research the findings showed that there was no correlation to shaft droop or shaft deflection, however there was a massive correlation in the shaft twist parameter.  GEARs defines shaft twist as: axial rotation down the golf shaft between the club's grip and club's head. This measurement is reported in degrees and is an angular magnitude.
As a note - most will simply refer to this as "shaft torque" as has the entire shaft industry, however, I'll take this moment to point out that torque is an external force that is applied to a body.  You can torque a shaft, but a shaft doesnt have torque.  Torque is a measurement in Newton meter or Pound feet.  Yet the shaft industry tries to say torque is a measurement in degrees.  GEARs uses shaft twist and provides that number in degrees.
My research showed that there is a direct correlation between how much a player loves their putter to how little the shaft twists.  You can take that statement to the bank.  The most stable the putter shaft is from start to top of backswing, to impact, the more a player will like that putter.  When the shaft twists either clockwise, or counterclockwise, the timing aspect of that putter is not a desirable trait.
Now the real question is - what are the best shafts?  well, that depends.  I have seen some players use a stock smooth non-stepped putter shaft and have little twist, and i've seen the same have massive amounts of twist. 
The old school - 1980's and prior - ping stepped shafts - when tipped - were some of the most stable I've measured.
More current shafts, the Stability, Sack Parente, LAGP, and Accra putter shafts have yet to show any poor results and all seem to be a warranted purchase as they are all very very stable.
Steel wise, the KBS CT Tour putter shaft stood out as an excellent choice.  Fluted steel shafts are also better than non fluted.
Shafts I would stay away from are smooth non stepped steel shafts, stroke lab (low % of good results but there were some), anything that feels 'soft' or 'whippy.'
Stepped steel is better than non stepped steel, but still would avoid.
Overall stiffness is not direct indicator of stability, but it does serve as a factor.
I've attached a link to show how the shaft twist is measured below in comparing two different shafts.  The desirable graph is a flat line showing minimal to no axial twist of the shaft as in the gold shaft.  Blue shaft is one that is twisting the shaft closed, then opening on the downswing.  Very unreliable and difficult to form a consistent feel with.  The vertical dotted line on the left is top of the backswing, and the right one is impact. These putts were both swung at 5.20mph chs with grip speed of 1.63mph (gold) and 5.11mph chs with grip speed of 1.60mph (blue).  The gold shaft twisted a total of 0.13* while the blue was over 2.00*
 
 
Always appreciate the conversations here at MGS, hope this can add some color to the discussion.    

Measuring putter shafts has become one of my most fascinating research items to date.  Reading some of the commentary here I appreciate everyone's desire (psychosis 🙃) in improving tech. 
There are only 2 machines designed to measure the shaft in time and space during a swing/stroke - GEARs being the one I have, and fuji's enso the other.  I've worked with multiple manufacturers as well as client testing putters where we look at their favorite gamer club, and compare it to their most hated gamer club. In that research the findings showed that there was no correlation to shaft droop or shaft deflection, however there was a massive correlation in the shaft twist parameter.  GEARs defines shaft twist as: axial rotation down the golf shaft between the club's grip and club's head. This measurement is reported in degrees and is an angular magnitude.
As a note - most will simply refer to this as "shaft torque" as has the entire shaft industry, however, I'll take this moment to point out that torque is an external force that is applied to a body.  You can torque a shaft, but a shaft doesnt have torque.  Torque is a measurement in Newton meter or Pound feet.  Yet the shaft industry tries to say torque is a measurement in degrees.  GEARs uses shaft twist and provides that number in degrees.
My research showed that there is a direct correlation between how much a player loves their putter to how little the shaft twists.  You can take that statement to the bank.  The most stable the putter shaft is from start to top of backswing, to impact, the more a player will like that putter.  When the shaft twists either clockwise, or counterclockwise, the timing aspect of that putter is not a desirable trait.
Now the real question is - what are the best shafts?  well, that depends.  I have seen some players use a stock smooth non-stepped putter shaft and have little twist, and i've seen the same have massive amounts of twist. 
The old school - 1980's and prior - ping stepped shafts - when tipped - were some of the most stable I've measured.
More current shafts, the Stability, Sack Parente, LAGP, and Accra putter shafts have yet to show any poor results and all seem to be a warranted purchase as they are all very very stable.
Steel wise, the KBS CT Tour putter shaft stood out as an excellent choice.  Fluted steel shafts are also better than non fluted.
Shafts I would stay away from are smooth non stepped steel shafts, stroke lab (low % of good results but there were some), anything that feels 'soft' or 'whippy.'
Stepped steel is better than non stepped steel, but still would avoid.
Overall stiffness is not direct indicator of stability, but it does serve as a factor.
I've attached a link to show how the shaft twist is measured below in comparing two different shafts.  The desirable graph is a flat line showing minimal to no axial twist of the shaft as in the gold shaft.  Blue shaft is one that is twisting the shaft closed, then opening on the downswing.  Very unreliable and difficult to form a consistent feel with.  The vertical dotted line on the left is top of the backswing, and the right one is impact. These putts were both swung at 5.20mph chs with grip speed of 1.63mph (gold) and 5.11mph chs with grip speed of 1.60mph (blue).  The gold shaft twisted a total of 0.13* while the blue was over 2.00*
 
 
Always appreciate the conversations here at MGS, hope this can add some color to the discussion.    

Did you watch the video I posted?  Those were ~10 foot putts.  Euclidean math points out that 1* offline at 10 feet =2.07", the blue shaft in the video twisted in excess of 2*.  These aren't things to be skeptical about, i'm just showing the data I captured
Re: 'flex' of the shaft - we can measure the shaft in 3 planes of motion.  Twist is the only one I find to be significant in putting as the face has the greatest influence on the start line of the ball.  The other two directions are measured in millimeters of deflection (face forward ie adding loft) and millimeters of droop (toe down).  These two are hugely important in the dynamic loft and dynamic lie angle, however because of the speed of the putter head being swung and cg location to the shaft, putter shafts don't droop or deflect to any significant number.  Here are the deflection and droop of two shafts at impact.  The black stock, is the blue shaft from above, which is not as stable at impact as the lagp shaft, but it's still not significant in my world as the twist number is.  
 

 
As far as fitting a client to a putter, one has to calibrate to whatever they decide to hold in their hands.  The data i've compiled shows that putters that twist less for a player are easier to calibrate to than those that twist more, and players who like their putters the most, have putters with shafts with low twisting results. 

Did you watch the video I posted?  Those were ~10 foot putts.  Euclidean math points out that 1* offline at 10 feet =2.07", the blue shaft in the video twisted in excess of 2*.  These aren't things to be skeptical about, i'm just showing the data I captured
Re: 'flex' of the shaft - we can measure the shaft in 3 planes of motion.  Twist is the only one I find to be significant in putting as the face has the greatest influence on the start line of the ball.  The other two directions are measured in millimeters of deflection (face forward ie adding loft) and millimeters of droop (toe down).  These two are hugely important in the dynamic loft and dynamic lie angle, however because of the speed of the putter head being swung and cg location to the shaft, putter shafts don't droop or deflect to any significant number.  Here are the deflection and droop of two shafts at impact.  The black stock, is the blue shaft from above, which is not as stable at impact as the lagp shaft, but it's still not significant in my world as the twist number is.  
 

 
As far as fitting a client to a putter, one has to calibrate to whatever they decide to hold in their hands.  The data i've compiled shows that putters that twist less for a player are easier to calibrate to than those that twist more, and players who like their putters the most, have putters with shafts with low twisting results. 

The weight of the clubhead and the cg of the club head moving in an arc will twist the shaft against the grip bends the shaft in all 3 planes of motion (6DoF).  There is some flexing as I posted in my previous post in toe droop and face deflection, but those are not zero, and it's also not significant.  The shaft twist is the significant variable from the research.
 
The torsional strength is what regulates the shaft twist.  since steel is a homogeneous material, it's properties are only influence by wall thickness, taper, and steps.  A graphite composite can have more layers placed, at different angles to reduce this twist.  Engineers use composite materials in order to control motion in these three planes,
 
Everything I'm discussing is prior to contact.  Once you have first touch, the ball has been given it's orders.  I'm concerned on shafts being stable to ensure better impact alignments

Measuring putter shafts has become one of my most fascinating research items to date.  Reading some of the commentary here I appreciate everyone's desire (psychosis 🙃) in improving tech. 
There are only 2 machines designed to measure the shaft in time and space during a swing/stroke - GEARs being the one I have, and fuji's enso the other.  I've worked with multiple manufacturers as well as client testing putters where we look at their favorite gamer club, and compare it to their most hated gamer club. In that research the findings showed that there was no correlation to shaft droop or shaft deflection, however there was a massive correlation in the shaft twist parameter.  GEARs defines shaft twist as: axial rotation down the golf shaft between the club's grip and club's head. This measurement is reported in degrees and is an angular magnitude.
As a note - most will simply refer to this as "shaft torque" as has the entire shaft industry, however, I'll take this moment to point out that torque is an external force that is applied to a body.  You can torque a shaft, but a shaft doesnt have torque.  Torque is a measurement in Newton meter or Pound feet.  Yet the shaft industry tries to say torque is a measurement in degrees.  GEARs uses shaft twist and provides that number in degrees.
My research showed that there is a direct correlation between how much a player loves their putter to how little the shaft twists.  You can take that statement to the bank.  The most stable the putter shaft is from start to top of backswing, to impact, the more a player will like that putter.  When the shaft twists either clockwise, or counterclockwise, the timing aspect of that putter is not a desirable trait.
Now the real question is - what are the best shafts?  well, that depends.  I have seen some players use a stock smooth non-stepped putter shaft and have little twist, and i've seen the same have massive amounts of twist. 
The old school - 1980's and prior - ping stepped shafts - when tipped - were some of the most stable I've measured.
More current shafts, the Stability, Sack Parente, LAGP, and Accra putter shafts have yet to show any poor results and all seem to be a warranted purchase as they are all very very stable.
Steel wise, the KBS CT Tour putter shaft stood out as an excellent choice.  Fluted steel shafts are also better than non fluted.
Shafts I would stay away from are smooth non stepped steel shafts, stroke lab (low % of good results but there were some), anything that feels 'soft' or 'whippy.'
Stepped steel is better than non stepped steel, but still would avoid.
Overall stiffness is not direct indicator of stability, but it does serve as a factor.
I've attached a link to show how the shaft twist is measured below in comparing two different shafts.  The desirable graph is a flat line showing minimal to no axial twist of the shaft as in the gold shaft.  Blue shaft is one that is twisting the shaft closed, then opening on the downswing.  Very unreliable and difficult to form a consistent feel with.  The vertical dotted line on the left is top of the backswing, and the right one is impact. These putts were both swung at 5.20mph chs with grip speed of 1.63mph (gold) and 5.11mph chs with grip speed of 1.60mph (blue).  The gold shaft twisted a total of 0.13* while the blue was over 2.00*
 
 
Always appreciate the conversations here at MGS, hope this can add some color to the discussion.    

The weight of the clubhead and the cg of the club head moving in an arc will twist the shaft against the grip bends the shaft in all 3 planes of motion (6DoF).  There is some flexing as I posted in my previous post in toe droop and face deflection, but those are not zero, and it's also not significant.  The shaft twist is the significant variable from the research.
 
The torsional strength is what regulates the shaft twist.  since steel is a homogeneous material, it's properties are only influence by wall thickness, taper, and steps.  A graphite composite can have more layers placed, at different angles to reduce this twist.  Engineers use composite materials in order to control motion in these three planes,
 
Everything I'm discussing is prior to contact.  Once you have first touch, the ball has been given it's orders.  I'm concerned on shafts being stable to ensure better impact alignments

The weight of the clubhead and the cg of the club head moving in an arc will twist the shaft against the grip bends the shaft in all 3 planes of motion (6DoF).  There is some flexing as I posted in my previous post in toe droop and face deflection, but those are not zero, and it's also not significant.  The shaft twist is the significant variable from the research.
 
The torsional strength is what regulates the shaft twist.  since steel is a homogeneous material, it's properties are only influence by wall thickness, taper, and steps.  A graphite composite can have more layers placed, at different angles to reduce this twist.  Engineers use composite materials in order to control motion in these three planes,
 
Everything I'm discussing is prior to contact.  Once you have first touch, the ball has been given it's orders.  I'm concerned on shafts being stable to ensure better impact alignments

Measuring putter shafts has become one of my most fascinating research items to date.  Reading some of the commentary here I appreciate everyone's desire (psychosis 🙃) in improving tech. 
There are only 2 machines designed to measure the shaft in time and space during a swing/stroke - GEARs being the one I have, and fuji's enso the other.  I've worked with multiple manufacturers as well as client testing putters where we look at their favorite gamer club, and compare it to their most hated gamer club. In that research the findings showed that there was no correlation to shaft droop or shaft deflection, however there was a massive correlation in the shaft twist parameter.  GEARs defines shaft twist as: axial rotation down the golf shaft between the club's grip and club's head. This measurement is reported in degrees and is an angular magnitude.
As a note - most will simply refer to this as "shaft torque" as has the entire shaft industry, however, I'll take this moment to point out that torque is an external force that is applied to a body.  You can torque a shaft, but a shaft doesnt have torque.  Torque is a measurement in Newton meter or Pound feet.  Yet the shaft industry tries to say torque is a measurement in degrees.  GEARs uses shaft twist and provides that number in degrees.
My research showed that there is a direct correlation between how much a player loves their putter to how little the shaft twists.  You can take that statement to the bank.  The most stable the putter shaft is from start to top of backswing, to impact, the more a player will like that putter.  When the shaft twists either clockwise, or counterclockwise, the timing aspect of that putter is not a desirable trait.
Now the real question is - what are the best shafts?  well, that depends.  I have seen some players use a stock smooth non-stepped putter shaft and have little twist, and i've seen the same have massive amounts of twist. 
The old school - 1980's and prior - ping stepped shafts - when tipped - were some of the most stable I've measured.
More current shafts, the Stability, Sack Parente, LAGP, and Accra putter shafts have yet to show any poor results and all seem to be a warranted purchase as they are all very very stable.
Steel wise, the KBS CT Tour putter shaft stood out as an excellent choice.  Fluted steel shafts are also better than non fluted.
Shafts I would stay away from are smooth non stepped steel shafts, stroke lab (low % of good results but there were some), anything that feels 'soft' or 'whippy.'
Stepped steel is better than non stepped steel, but still would avoid.
Overall stiffness is not direct indicator of stability, but it does serve as a factor.
I've attached a link to show how the shaft twist is measured below in comparing two different shafts.  The desirable graph is a flat line showing minimal to no axial twist of the shaft as in the gold shaft.  Blue shaft is one that is twisting the shaft closed, then opening on the downswing.  Very unreliable and difficult to form a consistent feel with.  The vertical dotted line on the left is top of the backswing, and the right one is impact. These putts were both swung at 5.20mph chs with grip speed of 1.63mph (gold) and 5.11mph chs with grip speed of 1.60mph (blue).  The gold shaft twisted a total of 0.13* while the blue was over 2.00*
 
 
Always appreciate the conversations here at MGS, hope this can add some color to the discussion.    

The weight of the clubhead and the cg of the club head moving in an arc will twist the shaft against the grip bends the shaft in all 3 planes of motion (6DoF).  There is some flexing as I posted in my previous post in toe droop and face deflection, but those are not zero, and it's also not significant.  The shaft twist is the significant variable from the research.
 
The torsional strength is what regulates the shaft twist.  since steel is a homogeneous material, it's properties are only influence by wall thickness, taper, and steps.  A graphite composite can have more layers placed, at different angles to reduce this twist.  Engineers use composite materials in order to control motion in these three planes,
 
Everything I'm discussing is prior to contact.  Once you have first touch, the ball has been given it's orders.  I'm concerned on shafts being stable to ensure better impact alignments

that's a hard and fast unfortunate no.  If I could predict shaft data (full swing or otherwise) I'd be calling numbers in Vegas.
That said, putter data is showing that these putter shafts that have been introduced in the marketplace over the last ~5 years are effective.
Also, measuring the shaft's participation in the swing is quite easy and effective. 

Measuring putter shafts has become one of my most fascinating research items to date.  Reading some of the commentary here I appreciate everyone's desire (psychosis 🙃) in improving tech. 
There are only 2 machines designed to measure the shaft in time and space during a swing/stroke - GEARs being the one I have, and fuji's enso the other.  I've worked with multiple manufacturers as well as client testing putters where we look at their favorite gamer club, and compare it to their most hated gamer club. In that research the findings showed that there was no correlation to shaft droop or shaft deflection, however there was a massive correlation in the shaft twist parameter.  GEARs defines shaft twist as: axial rotation down the golf shaft between the club's grip and club's head. This measurement is reported in degrees and is an angular magnitude.
As a note - most will simply refer to this as "shaft torque" as has the entire shaft industry, however, I'll take this moment to point out that torque is an external force that is applied to a body.  You can torque a shaft, but a shaft doesnt have torque.  Torque is a measurement in Newton meter or Pound feet.  Yet the shaft industry tries to say torque is a measurement in degrees.  GEARs uses shaft twist and provides that number in degrees.
My research showed that there is a direct correlation between how much a player loves their putter to how little the shaft twists.  You can take that statement to the bank.  The most stable the putter shaft is from start to top of backswing, to impact, the more a player will like that putter.  When the shaft twists either clockwise, or counterclockwise, the timing aspect of that putter is not a desirable trait.
Now the real question is - what are the best shafts?  well, that depends.  I have seen some players use a stock smooth non-stepped putter shaft and have little twist, and i've seen the same have massive amounts of twist. 
The old school - 1980's and prior - ping stepped shafts - when tipped - were some of the most stable I've measured.
More current shafts, the Stability, Sack Parente, LAGP, and Accra putter shafts have yet to show any poor results and all seem to be a warranted purchase as they are all very very stable.
Steel wise, the KBS CT Tour putter shaft stood out as an excellent choice.  Fluted steel shafts are also better than non fluted.
Shafts I would stay away from are smooth non stepped steel shafts, stroke lab (low % of good results but there were some), anything that feels 'soft' or 'whippy.'
Stepped steel is better than non stepped steel, but still would avoid.
Overall stiffness is not direct indicator of stability, but it does serve as a factor.
I've attached a link to show how the shaft twist is measured below in comparing two different shafts.  The desirable graph is a flat line showing minimal to no axial twist of the shaft as in the gold shaft.  Blue shaft is one that is twisting the shaft closed, then opening on the downswing.  Very unreliable and difficult to form a consistent feel with.  The vertical dotted line on the left is top of the backswing, and the right one is impact. These putts were both swung at 5.20mph chs with grip speed of 1.63mph (gold) and 5.11mph chs with grip speed of 1.60mph (blue).  The gold shaft twisted a total of 0.13* while the blue was over 2.00*
 
 
Always appreciate the conversations here at MGS, hope this can add some color to the discussion.    

Measuring putter shafts has become one of my most fascinating research items to date.  Reading some of the commentary here I appreciate everyone's desire (psychosis 🙃) in improving tech. 
There are only 2 machines designed to measure the shaft in time and space during a swing/stroke - GEARs being the one I have, and fuji's enso the other.  I've worked with multiple manufacturers as well as client testing putters where we look at their favorite gamer club, and compare it to their most hated gamer club. In that research the findings showed that there was no correlation to shaft droop or shaft deflection, however there was a massive correlation in the shaft twist parameter.  GEARs defines shaft twist as: axial rotation down the golf shaft between the club's grip and club's head. This measurement is reported in degrees and is an angular magnitude.
As a note - most will simply refer to this as "shaft torque" as has the entire shaft industry, however, I'll take this moment to point out that torque is an external force that is applied to a body.  You can torque a shaft, but a shaft doesnt have torque.  Torque is a measurement in Newton meter or Pound feet.  Yet the shaft industry tries to say torque is a measurement in degrees.  GEARs uses shaft twist and provides that number in degrees.
My research showed that there is a direct correlation between how much a player loves their putter to how little the shaft twists.  You can take that statement to the bank.  The most stable the putter shaft is from start to top of backswing, to impact, the more a player will like that putter.  When the shaft twists either clockwise, or counterclockwise, the timing aspect of that putter is not a desirable trait.
Now the real question is - what are the best shafts?  well, that depends.  I have seen some players use a stock smooth non-stepped putter shaft and have little twist, and i've seen the same have massive amounts of twist. 
The old school - 1980's and prior - ping stepped shafts - when tipped - were some of the most stable I've measured.
More current shafts, the Stability, Sack Parente, LAGP, and Accra putter shafts have yet to show any poor results and all seem to be a warranted purchase as they are all very very stable.
Steel wise, the KBS CT Tour putter shaft stood out as an excellent choice.  Fluted steel shafts are also better than non fluted.
Shafts I would stay away from are smooth non stepped steel shafts, stroke lab (low % of good results but there were some), anything that feels 'soft' or 'whippy.'
Stepped steel is better than non stepped steel, but still would avoid.
Overall stiffness is not direct indicator of stability, but it does serve as a factor.
I've attached a link to show how the shaft twist is measured below in comparing two different shafts.  The desirable graph is a flat line showing minimal to no axial twist of the shaft as in the gold shaft.  Blue shaft is one that is twisting the shaft closed, then opening on the downswing.  Very unreliable and difficult to form a consistent feel with.  The vertical dotted line on the left is top of the backswing, and the right one is impact. These putts were both swung at 5.20mph chs with grip speed of 1.63mph (gold) and 5.11mph chs with grip speed of 1.60mph (blue).  The gold shaft twisted a total of 0.13* while the blue was over 2.00*
 
 
Always appreciate the conversations here at MGS, hope this can add some color to the discussion.    

Measuring putter shafts has become one of my most fascinating research items to date.  Reading some of the commentary here I appreciate everyone's desire (psychosis 🙃) in improving tech. 
There are only 2 machines designed to measure the shaft in time and space during a swing/stroke - GEARs being the one I have, and fuji's enso the other.  I've worked with multiple manufacturers as well as client testing putters where we look at their favorite gamer club, and compare it to their most hated gamer club. In that research the findings showed that there was no correlation to shaft droop or shaft deflection, however there was a massive correlation in the shaft twist parameter.  GEARs defines shaft twist as: axial rotation down the golf shaft between the club's grip and club's head. This measurement is reported in degrees and is an angular magnitude.
As a note - most will simply refer to this as "shaft torque" as has the entire shaft industry, however, I'll take this moment to point out that torque is an external force that is applied to a body.  You can torque a shaft, but a shaft doesnt have torque.  Torque is a measurement in Newton meter or Pound feet.  Yet the shaft industry tries to say torque is a measurement in degrees.  GEARs uses shaft twist and provides that number in degrees.
My research showed that there is a direct correlation between how much a player loves their putter to how little the shaft twists.  You can take that statement to the bank.  The most stable the putter shaft is from start to top of backswing, to impact, the more a player will like that putter.  When the shaft twists either clockwise, or counterclockwise, the timing aspect of that putter is not a desirable trait.
Now the real question is - what are the best shafts?  well, that depends.  I have seen some players use a stock smooth non-stepped putter shaft and have little twist, and i've seen the same have massive amounts of twist. 
The old school - 1980's and prior - ping stepped shafts - when tipped - were some of the most stable I've measured.
More current shafts, the Stability, Sack Parente, LAGP, and Accra putter shafts have yet to show any poor results and all seem to be a warranted purchase as they are all very very stable.
Steel wise, the KBS CT Tour putter shaft stood out as an excellent choice.  Fluted steel shafts are also better than non fluted.
Shafts I would stay away from are smooth non stepped steel shafts, stroke lab (low % of good results but there were some), anything that feels 'soft' or 'whippy.'
Stepped steel is better than non stepped steel, but still would avoid.
Overall stiffness is not direct indicator of stability, but it does serve as a factor.
I've attached a link to show how the shaft twist is measured below in comparing two different shafts.  The desirable graph is a flat line showing minimal to no axial twist of the shaft as in the gold shaft.  Blue shaft is one that is twisting the shaft closed, then opening on the downswing.  Very unreliable and difficult to form a consistent feel with.  The vertical dotted line on the left is top of the backswing, and the right one is impact. These putts were both swung at 5.20mph chs with grip speed of 1.63mph (gold) and 5.11mph chs with grip speed of 1.60mph (blue).  The gold shaft twisted a total of 0.13* while the blue was over 2.00*
 
 
Always appreciate the conversations here at MGS, hope this can add some color to the discussion.    

Well people, your all just not carrying out in instructions correctly! No back problems, digits after the ball, better strike, better ball flight, equals extra distance.. 
MANY thanks S&T

I was with the person who took these photos, and have done extensive testing of gears with the stealth.  The face does not pass the fingernail test as defined by the usga.  Tees leave a mark as does your finger.  I have no idea how tm got away with this.  
Side note. Carbon doesn't spin, so the "jelly" face is adding spin to make the carbon usable as a face material.

Graphite Design had some as did the GEARs booth on the etc range 

Well, as long as its your driver and NOT mine, then we can agree on that. 😂

I was with the person who took these photos, and have done extensive testing of gears with the stealth.  The face does not pass the fingernail test as defined by the usga.  Tees leave a mark as does your finger.  I have no idea how tm got away with this.  
Side note. Carbon doesn't spin, so the "jelly" face is adding spin to make the carbon usable as a face material.

I went to our local golf shop here in San Diego Friday evening and was just looking around. I walked up to the Stealths as I was mostly checking out the 3 woods which was the only one I would consider. The sales guy came up and said something like, wow, the Stealths........I said nah, not looking at the drivers just the 3 woods.......he said something like, good, our test heads faces are already turning orangish/white with all the hits....I said, I've heard about face issues and seen that the face can scar or indent......he then said yeah, I would not buy one, have you checked out the new Cobra's and Rogues..........
100% honest to GOD story fellas............

There may be some truth to this new Korean firm that bought Taylormade in May of 2021.......

Reposting the usga rules as written as a courtesy.  
 
Yes it left a mark. 

Fingernail test
received_662360118230669.mp4

Fingernail test
received_662360118230669.mp4