MBoy,

Getting the trim just right for aerobatics is a very personal matter. No two people will agree on exactly the best settings.

First, I am confused at why you are using rudder, since you said it rolls perfectly axial without rudder correction? At any rate, I suspect the mixing you set up for knife edge is interferring with your rolling.

As you reach the first knife edge in a roll, you would normally be easing forward on the stick so the wing lift becomes zero. If it turns to the belly at this point, you are pushing forward too fast. When you get inverted, you will push more on elevator to produce negative lift. If it doesn't turn to the belly at the second knife edge, then your timing is perfect for that segment.

Personally, I don't use any mixes. I just watch the plane and add whatever corrections are needed for each manuever.

Tom