Well, I'll have to chime in on the 5645. It has good torque, but on an aerobatic plane I found out the hard way ($$) that they are relatively slow and possibly the centering isn't as good as some other servos. Maybe the Power HD1501 servos would be good for the Cessna. They claim over 200 oz. at 6V. and the speed is faster than the Hitec. And the price is very reasonable.