RE: good prop after evo trainer?
Lots of good choices mentioned above. Don't be afraid to try things. You won't hurt anything unless you get silly.
As for aileron flutter, I've flown in to it, and mananged to slow down with no problems. I've also had the flutter start suddenly and imeditally strip the aileron servo gears. That was a fun landing, since it was on a combat plane that has no rudder. I've also seen flutter quickly cause the control surface to part company with the rest of the plane. When it's the elevator, the results are predictably dramatic.