lynnpreston,
I think the wing tips improved the overall characteristic in a positive way. Harriers are more stable, inverted flat spins are a riot. Just go vertical and throw both sticks in the upper right corner. She'll flip inverted and flat spins on the spot for ever with throttle wide open. The insane roll rate is still insane, although perhaps a tad tamer. I only can recommend this mod to all Twist owners. Took me only a couple of hours to complete.