As far as what mixes, the only thing I do is, after setting up proper CG, thrust, aileron differential, lateral balance and such, I roll to knife edge at half throttle or so and input only enough rudder to maintain altitude and watch what happens. I then mix the appropriate amount of (typically opposite) aileron so that I can fly horizon to horizon with virtually no aileron input. I also mix the appropriate direction and amount of elevator to do the same. After I get it pretty close, I attempt a flat turn with the same amount of rudder and make sure the plane doesn't want to climb, drop or roll. Beyond that, the only other mixes I use are throttle/elevator mix for straighter downlines. When it comes to the snap, I don't know of anyone that has special programmable mixes they use specifically for snaps. However, I do have a specific flight mode that I use for snaps, that limits the throws to an amount that I had to experiment with. With a typical aerobatic plane, a proper snap only requires a low rate rudder and elevator, and a medium-to-low rate on the ailerons. I am not sure this helps you but it is the only mixes I ever set up on my plane, and I think it's the same for most people.