Ralph can answer all questions, but I have som answers, I think
The flex and flex profile of a shaft will change the spin and angle of attack.
If you have a tip stiff shaft with a high bend point like the TT DG you will get less whip through the ball and less acceleration through the ball. more of a steady speed and angle of attack at impact. This translates more easily to a lower ball flight with less spin. If you have a softer tip and a lower bend point you can experience more acceleration and more whip through the ball. The clubhead whips through on a smaller circle. This can result in a clubhead passing the rest of the shaft throug impact, adding positive angle to the flight. The clubhead will also cut vertically more and set more spin on the ball.
Softness is depending on how much you are able to bend it, not the actual flex. High SS, stiffer shaft will do the same as slower SS and softer shafts.
