A little searching will probably get you a manual for your sailplane with torque recommendations for servos. If you don't know what it is, post a couple of pics in the Q&A forum and you'll probably find out in a few hours. FWIW, I know you want to save money but going ahead and springing for the ball bearing supported servos is money well spent. It's only $15-20 extra for the entire airplane and you'll get servos that can take a lot more abuse before they get sloppy and start wearing out their gears. If you're the money saving type, you probably also are the use servos until they fail type, so going ahead and buying good ones will save you some trouble and some money in the long run. I wouldn't worry about the tougher servos for the sailplane, but definitely for the .60 size sport plane.