While you could use HS-81's (based on their torque rating), I wouldn't. The HS-81's have a fairly weak gear train, and will easily strip if you get a touch of flutter or even bump the aileron just wong (hanger rash). I use a lot of HS-81's, but generally on throttles. There is a metal gear version that fixes that problem, but it's more expensive. If it was me, I'd go with the servos you mentioned, or maybe spring for something in the HS-4xx line. Not that you'd notice a difference in performace on a trainer's ailerons.