Don't forget FMA direct (FS8) and Berg (7p). I think Sombra Labs might have one in the works. FMA and Berg (Castle Creations) are the onlyI know of that have failsafe. Multiplex IPD, I've read complaints about it being lower in resolution, and having a noticable delay vs PPM.

http://www.castlecreations.com/
http://www.fmadirect.com/

You can also get failsafe additions that go between the reciever and the servo for an individual channel, commonly used in glow powered cars. I think there was a setup that went between the receiver and the servos on all channels, allowing one to boost the voltage going into the servos beyond 6 volts, it took the current drain off the reciever, and added a failsafe. Zebra comes to mind... [sm=confused.gif]

About 2.4 Ghz, they're having difficulty deciding on a standard. I read some tests have resulted in interference with other brands. AMA is getting involved.