I know my Dx6i can be hooked up to another 2.4 ghz as long as its spectrum. I believe one of the instructors at the club has a DX7 so I should be fine. How much work are the retracts and how do they work? I know you need an extra servo and the retract system. Dave Brown something? Do these tend to go in fairly easy? I need to look up some things. Im hoping the LHS will have the system I need. When I go to pick up the training I might ask. 6 channels is enough for retracts correct? I think you only need 5?