Hi Gordie.
In general, torque and accuracy are both improved together, and most important.
Speed is critical (in my opinion) on the elevator. A fast elevator enhances the pitch break in the snaps.
Of course, if the elevator doesn't have enough torque behind the quick movement, then you lose the speed benefit, anyway.
The only option, in that case, is a servo that is both fast and powerful.
Maybe you could use two fast servos, one on each elevator half.
Later,
Dean