RE: What's the advantage of dual aileron servos?
For your Nexstar? Well you get to spend another $13.95 for a servo. and about $4 for a y harness and You may need two $3 servo extention wires. So the hobby shop will have all the advantage. Once you get a Computer radio you can learn how to mix flapperons/spoilerons (worthless on a Nexstar) by using channels 1 and 6 instead of the Y-Harness.