The 517 is a standard servo and I use them in a number of positions. J. Buckner gave you a good run-down.

I don't mix servo brands on same surfaces like ailerons. There have been some that mix brands such as Hitec and Futaba (maybe it's JR) on elevators because they rotate different directions and therefore no need for servo reversal wiring.

The 517 will do well on any application that can use such size servo. On ships up to 45 power, I find 2 standard servos, 4050 oz. torque work very well on elevators or ailerons and 1 functions fine for rudder/nosewheel/ or throttle. Heck back in the '70s one servo working both ailerons was the norm, even on the .60 size pattern machines. Back then a servo cost 40-50 yankee dollars and that was a lot of money, in the '70s.

Lots of marketing hype in the servo world. Lots of relative newbies hear the field-deep-pockets-"expert" say something so relative newbs repeat such as they also become instant experts.