I had a few quivering HS-55's, and the one I totally stripped by bouncing the rudder on the ground in the pits. Great on electric parkies, but I would avoid them with glow.

I've used the HS65's on up to .15 tail surfaces, I flog the crap out of them on electrics, and on several 1/2A's. I really like them. It was Combatpigg who first trumpeted their virtues on this forum, maybe 7-8 years ago, and I own more of them now than any other small servo.

The Dymond 6.0 and 4.7 are known to be pretty tough little servos. I have a couple of D60, great servos and I believe they would do the job great on 1/2A's, but I only have experience with two so far so that's only an opinion. I know I would have bought a handful of D60's had the HS65's not come along.