I've used these servos in all my fast sailplanes up to 3 meters with absolutely no problem. And the sailplanes are much faster (120 mph in dives) and have higher servo loads than a fun fly ever will. In fact I've never had a stripped gear, even in a crash. I think gear failures reported in association with flutter are stripped due to the flutter loads, and are not themselves the root cause of the flutter. Flutter is an aeroelastic effect which is caused by loose hinging, lack of gap seal, or improper aerodynamic design of the control surface. An efficient control surface at zero angle of attack should require very little holding torque and cause littel stress on the gears.
Also, aren't HS-85's really popular among competition fun flyers?