[If they changed the rules tomorrow...]

A fifth wedge. Probably double up on the 52° with different grind/bounce or add a 64° and look at pairing it against the grind/bounce on my 60°.  I could use something to hit out of the nasty thick and tall.  

[Ball spin on mid iron shots and 50 yards and in....does it mean anything?]

Rpm is a measurement of rate of rotation. How long it’s in flight is only going to change how long it can affect the ball flight, not how much affect per second. 
 

the spin is a direct result of multiple factors, including loft at impact, compression, friction, etc.  but all other things being equal, the cause of the spin differences from ball to ball are greatly coming from coefficient of friction differences between the ball and the club face. This implies a relationship between launch angle and the spinny-ness of a ball, too, as the friction will interact with the trigonometry relative to the normal vector between the ball and the club face at impact. 
 

so you have a different launch angle, different behavior in the air, and different behavior on landing.  Seems pretty clear that spin is a big factor in the things you care about.