RE: Sig Extra 300sx SET UP QUESTIONS
I never had any problems with flutter, or the airplane snapping. The easiest way to seal the aileron gap on this plane is clear packaging tape. I flew mine with Futaba 9202 servos all around. I used the radio to set up both elevator servos (also an 8UAP) and didn't use a Miracle Y. I sold the airplane this February.
I believe that the reason your plane is snapping is your stab and wing incidence isn't the same. When I put mine together, I had almost 2 degrees difference between the wing and stab, and had to sand the forward part of the stab saddle to get the incidence the same.
This is a very fun plane to fly. It'll do most aerobatics, won't 3D, but does wonderful Lomcevaks, Knife Edge Spins and Blenders. Never had any coupling problems either direction in Knife Edge either. Flew mine with an OS 1.60FX