I'm looking at both the Futaba 7C and 6EX 2.4Ghz radios for my first trainer plane.

I don't want to have to upgrade if I get to the 2nd and even 3rd plane. First of all, is that realistic, and second, if so, which radio would fit my needs.

I sure don't know what I'd use beyond the first four channels for throttle, rudder/nose gear, elevator and aelorons but I'm guessing the most I'd ever want would be
to add a channel for flaps and MAYBE one for something else, so I can't see beyond six channels. I have the money for the 7C so my question really is would I likely use the 7th channel or should I save the hundred bucks and go with the 6EX.

Any help with the differences between the two would also be appreciated.

Thanks in advance!