I've tried the mixing for knife-edge. It did make it a bit easier. However, I do think that switching the mix is necessary, since rudder corrections for wind or whatever in vertical manoeuvres (stall turns, square loops, etc.) will be affected by unwanted elevator or aileron inputs.

I tend to forget where all the switches are set, so I just fly the plane. It just seems more natural than having to change setup for each manoeuvre. I don't fly in competitions yet, and can barely get through the basic sequences so you may want to hear from more experienced flyers.