I doubt the flight loads on the elevator will be very high while hovering. In fact, I'm sure they're less than in forward flight. I'm guessing though that you'll lose some control precision with the flexing.

Most planes I've seen being used for 3D have independant sefvos for each elevator half (bigger stuff), or the elevator halves are tied together with a rod and controlled by a single servo or a pull/pull set-up.
Dennis-