I wouldn't use the 3003 type servos. Not only because they don't have bearings, but they might fail. I would get something with a little more torque as well. I wouldn't even use the 3003 on the throttle, but thats just me.

I would suggest jr 811's. They have the torque and are digital. they just might be a little expensive.

The tt50 seems pretty good to me so far, but I only have 3/4 a gallon through it and can't give you a good opinion.Both the os and the tt probably would be good. I got the tt 50 because it was cheaper, used less fuel and seemed like it ran out of the box. Too many people with the os 50 are doing carb mods or getting the 60b carb. I also heard it sucks up more fuel, but produces more power.