Daniel,
I have that plane with an OS91fs and it doesn't have "great" vertical. It is a very nice flyer with that engine and it's a beautiful plane. I'll be flying it today!

The servo power you need depends on how much control throw you want. When you setup for 3D deflections, you are lowering the mechanical advantage the servo has. This means you need more torque. If you want to have "high" rates, I would suggest a high torque servo for the rudder and elevator.

I am using one 9202 on the elevator and one on rudder.

Tom