The primary purpose of failsafe is not to save your model - it's to try to save someone's life. Having the ability to close the throttle when the aircraft is otherwise out of control means that you substantially reduce the killing power of the aircraft.

I've been shot down on PPM once, and watching the model scream towards the ground at full throttle and dig a hole 18 inches deep was a sufficiently scary experience that I immediately went out and bought a PCM system and programmed the failsafe for throttle kill.

Be careful what you read or get told about PCM - there are a whole bunch of ludicrous old wives tales around, because being totally ignorant of PCM's real behavior unfortunately does not lessen some folks' enthusiam for spreading their 'expertise" around.

See http://www.rcuniverse.com/forum/fb.asp?m=199627

Gordon