Gyros are not allowed.

Certainly BPLR apparently flys with very little throw on his control surfaces, so little power is needed.

I too would tend towards the high speed servo over the high torque to improve response, except the rudder where you do need the power, and the speed is less of an issue.

If you compare the size and depth of control surfaces, the elevator comes out at the smallest, so intuitively needs less torque than either the ailerons or rudder.