I know most guys crap on hi-tec, i agree totally BUT iv'e been running the HS925bb metal gear, and "touch wood" i've never had a problem with, it it's cheap @ $100 (In comparison to other high end servos) and also is very reliable as it was originally designed to be used with gyros on rc choppers which are quite fast (0.09sec @ 4.8v if my memory serves me correct)

FET field effect transistor.
more efficiant, faster switching speed.