RE: servos
Micro servos today are superior in every way to the standard heavy duty servos we used to use for 1/4 scale years ago. With 3D, lighter is better. I would not use the 81's in my plane if I were you, they have nylon gears and may strip on you. the 85mg are 10 grams heavier, for every servo you put in the tail you will have to add lead up front to compensate.