I really doubt it is weak servos, I have flown a TF giant P-47 with a g62 engine for 15 years with the same 70oz servos. I think 6mm throws are not enough. I usually set up planes with 3/4 inch up and down on ailerons and more on elevator sometimes. One caveat, I like active planes so that is more active than some others like. I also never use exponential because I learned to fly when there was 4 channels, no servo reversing or end point or dual rate, you learned how to be delicate with the sticks instead of depending on the radio to dampen out the reactions. Not against any of those things, just don't need them. I want my planes to react when I give them input, not feel like there is a rubber band between the servo and the surfaces. Just my opinion.
Larry