I would say it's pretty stable as long as you swing hard/fast, and hit the small but "sweet" sweetspot. Off center hits can be unstable (on hard hit balls) because of the Tour 10 mids small head, and flexible nature. I think adding a little lead tape should "cure" this though. Have hit with the PT 280 and Pro #1, but not long enough to do a comparo.
I've put 8g on my pro #1. 4 at 3 and 9 o'clock and 4g under the replacement grip.
My slices still don't stay low and heavy like they do when I use my Yonex MP Tour 1 98". If I switch racquets in the same tennis session my slice instantly improves with the Yonex. It must be the racquet!!!!!!!!!