I'm not certain, but it is probably noteworthy that with aids turned on (even at minimum?), the spin effects are reduced. So even getting past 12:00 o'clock may not result in what you expect, since the spin reduction aid(s) kicks in. You may need to go well past 12:00 o'clock to get additional power / increased spin with aids on. With the new Tour Pro level, you may have to go to "Custom" and turn off the aids to fully realize the effects of going past 12:00 o'clock.
This is not the case. There is no reduction of backspin at higher levels.