I don't think any mix is necessary, except maybe flapperon and spoileron with up and down elevator. When doing knife edge, flipping to a real low rate elevator helps to calm it down. I usually don't, so when it tucks a bit, I have to be really sensitive with the elevator, or it is all ov the sky. Mine is a bit tail heavy/happy, she pitches up when inverted, so how do I mix that out ha ha.
DKjens