My BobCat now has 3421's on the elevators. I originally built it for 3301's, then one day it fell off the table at the field, knocked the elevators and stripped the gears in the servos. The 3301's are plastic gears. I replaced them with 3421's which have metal gears. I'm sure the 3301's wouldn't break in flight, but I just feel better with the 3421's.

BTW, I installed a Matchbox on the elevators. It's really easy to set-up and has worked perfectly for about 10 flights so far.