If you're not having problems with your current stuff, and not having flying time conflicts with the other person, there's no real reason to change. Our club is small, and my brother and I are on channel 13. I have never even seen another transmitter on 13.
I'm not sure I would buy anything with the idea of sitting on it for several years before using it. Your 9C could "die" at any time. Probably not likely but definitely possible.
If you just "want" to switch to a 2.4 gHz setup,
Another combo worth looking at is the Hitec
http://www3.omnimodels.com/cgi-bin/w...I=HRCL4605&P=0
For $114.99, you get a seven channel module and TWO six channel receivers. The six channel receivers are regularly about $50 each so they are also practically giving away the modules.
I think Spektrum and Hitec are both playing a pretty smart game. They are putting together very attractive packages that are tough to ignore. I know Futaba has done some promotions with rebates and receiver deals but the ones I have seen do not really match what the competition is doing.