As a heads up, if you take your plane to some fields they will require an idle failsafe on the throttle... some even require 2 ways to kill the engine from the TX.

You can do the failsafe several ways:
1) Multiplex IPD RX (What I have)
2) PCM RX
3) Hitec programmable digital servo
4) Aftermarket throttle failsafe device (I prefer not to add additional devices that I don't use on a normal basis... something else to fail)

You can do the engine kill several ways (low throttle counts as the first one):
1) Choke servo (my prefered method)
2) Optical kill switch
3) Mechanical kill switch

I don't think these are AMA required (don't quote me) but I think it may be going that way, especially the first one. I know Joe Nall requires the failsafe.