Brent
Yes you could be right, the SLE it may well be near constant. The "Aeson" driver likely has the max SLE allowed. I'd like to see data for the SLE contribution to the COR over a range of speeds. I have heard claims that the SLE only benefits the stronger players, but never seen any data to back it up. There are claims that weaker players don't benefit from the SLE because they don't hit the sweet spot often, which is where the club face has been optimized for SLE. Which seems to make sense, but again, I don't have any data as to how the SLE varies away from the sweet spot.
My understanding of the SLE is that the metal face of the club can snap back into shape with less losses than the ball. Which make sense if you think about the differences in the material... atomic bonds in a metal vs polymers. For a given impact speed, the ball will deform less with an SLE driver vs a rigid driver. But in terms of the COR of the collision, this is more than compensated for by the club face deforming and snapping back.
If you were building a ball for absolute max COR you want the ball to deform as little as possible to limit losses: roughly, the stresses in the ball are inversely proportional to the amount of deformation. So v small deformations will put huge stresses on the internal bonds...a stiff,strong, material like Ti in the club face can handle this, it will deform less and not shatter.
If there was no COR limit, I think you would see a greater push towards the hollow metal ball. A ball that recover its shape most efficiently.