Having been bitten a time or two too often by flutter, I use mass balancers on the ailerons and elevators of everything I build, and have have little trouble since. Addition of mass balancers can make even competition fun-fly models virtually flutter-proof, when without balancers, they would flutter badly at anything over 30 MPH or so. I have flown such models at speeds in excess of 100 MPH, with aileron chords over 4", without flutter, thanks to mass balancers with the right balance moment.