This got me inspired.
I just did an experiment with a Pure Storm Ltd.
I put two weights of 45 grams at the sides of the head and moved both up and down until I was satisfied with a constant launchangle when the tennisballs were hit across the face from 3 to 9. The most ideal spot seemed to be at 4 and 8. I know I varied not only twistweight but also swingweight and balance, but during play I also varied grip position up and down regardless of the present swingweight and balance.
The interesting part is that I tried to hit with constant rackethead speed and all over the racketface from 3 to 9 and with the weights attached at 4 and 8, the launchangle, speed and depth were pretty constant, which makes me believe that the spinrate also had to be pretty much the same. Whether a 425 grams racket is really playable is another question
Really looking forward to your experience, Corners.