If it didn't matter, then why do the OEM still highlight low-compression, high-compression, super soft core, etc. on their boxes? To me it sounds like it does matter, but they don't want the player to know the real number so they can't compare/classify their products.
On the other hand, I read that due to the different technologies in the core, mantle, cover, etc... the compression will feel different. For instance, Callaway Solaire is supposed to be a women's ball, but it has a higher compression than the BB Diablo. After hitting a Diablo and my wife's Solaire... I felt the Solaire was still softer and mushier. So how can that be?
And that is why I asked in the beginning... does matching your swing speed to a compression number still apply?
Take another example... I was at the pro shop testing out balls. I was looking at a premium ball.
You had the Callaway i(s), Srixon Z-Star and ProV1. The fitter recommended these 3 softer models for my swing speed (as opposed to the i(z), Z-Star XV and ProV1X for 100mph)
But if you look at the chart, the Z-Star XV has a similar compression to the i(s) and ProV1, so the rule wouldn't apply.
This makes finding the right ball so hard
GBB Epic 9* w/ Aldila Rogue MAX 65 S
X2 Hot 3 Deep 14.5* w/ Aldila Tour Green 75 S
JetSpeed 5W 19* w/ Matrix Velox T 69 S
Apex CF16 4-PW w/ PX 5.5 Steel
MP-T5 black IP 50/7, 54/12, 58/4 w/ DG Wedge
ER1 34" w/ SuperStroke Fatso 2.0
Sun Mountain H2NO Lite Cart Bag / Clicgear 3.0
My MLA putter review here // My ShotScope review here