If you plan to fly in a busy area, definitely get a radio with a module. Futaba is supposed to come out with a synthesized module for the 9C one of these days, and then you can tune any freq in the 72MHz band by turning a dial. I don't know all of the differences between the two... I have a 9C, and I helped a friend program his 7C. The 9C has a much better LCD display and a menus, and has a graphical display for heli throttle/pitch curves and for expo adjustments.

You might want to consider Hitec TXs... Hitec has a synth module out already for their radios. If you can get away with a 6ch computer TX, the Optic-6 looks like a good buy to me (see link below)... I'm considering it over the 7C for a second radio... no module in the 7C is a big turn-off for me.

http://www.servocity.com/html/6-ch_optic_6_systems.html