I agree 100%!! Bill was generous enough to send me a set to try a few weeks ago. They were only #37, and shot the same arrows as my #45 classic limbs nearly as fast. I took many pictures in comparison so my Evo and Classic limbs and had planned on writing a review, but my phone took a dunk in the lake.
The z4 design loads incredibly smooth and just like stated above, almost feels like it has a slight let off towards the end of the draw. It really allowed Me to settle into my anchor point comfortably and more consistently.
Bill has hit a home run here and after ten shots I immediatemy emailed him and sent a deposit to get in line for a set of my own.