If you set your servos up for maximum mechanical advantage, you will not have any problems.

The requirements are simple and you probably already do it. 1) Never turn the EPA/ATV on your transmitter below 100%. 2) Attach the pushrod in the outer hole of the control horn. 3) Attach the pushrod in the servo arm hole, closest to the center of the servo, that will still give you the travel you need. 4) Don't use Expo. If the airplane is too sensitive, reduce the travel.

Doing it this way, you can easily get a mechanical advantage of 3 : 1, giving your 42 oz standard servo the equivalent of 126 oz. servo, at the control surface.

For 3D, you need monster servos. For normal sport flying you don't.

Jim