RE: Secure channels for RC planes
I agree with your concerns. I would like to see the FCC limit the 72mhz band to organized model clubs, and put the "toys" all on the 27mhz band. There is a substantial difference. It's only a matter of time.
I fly with a club. The runway is 150 yards from the river. Directly across the river is a large park. I think it's only a matter of time until some one shoots one of us down.
The signature signal problem is not expensive, it's cumbersome. A few cents will add the signature to the transmitter and receiver that you buy together. Additional receivers purchased later, would have to be programmed. It' still do able however, and like most problems, they will fix it when they have to.