Don't know about the 5085, but I've tried the 5245's on ailerons on a 50-size.. After trying to set the centering to max accuracy using their servo programmer, the servos still would not center properly. Ended up with selling them cheap! Probably OK for throttle.

Jon Wold is the only person I know is using Hitech servos for F3A: http://www.aerowold.com/