NightHawke - I've had negative experiences with Bushmaster rifles too - the one I have has been fixed and since retired. Start with a quality weapon. Next - most people don't know how to clean their weapons. The old "IG, White Glove" inspections are BS. Keep the M-16/M-4 "functionally clean" and properly lubed and it will go thousands of rounds without a malfunction. As an LEO - even on a SWAT Team - what is the likelyhood that you will fire a tiny fraction of that even in training?
The only time mine gets "filthy" is when I'm playing with the suppressor. Not even a piston system will prevent that. Check out Larry Vickers' Tactical Tips (
http://www.vickerstactical.com/tacticaltips.htm). It'll save me a lot of typing and any differences I have with him are on the order of "happy - glad".
Start with a quality AR, maintain it properly, feed it quality ammo from quality magazines, and there is no real reason to buy a gas piston system except "I want one". (Wait a minute - didn't TR do a thorough discussion of this just recently?)
The Army's problems with the AR system are not going to be fixed by adopting a different weapon, gas piston or no. Most of the weapons I "played with" over the years were well beyond their useful life. Equipment, specifically weapons, break and/or wear out. They need replacement after a reasonable life cycle (read ROUND COUNT). When the military is willing to spend as much on small arms procurement, maintenance, and operator training as they do to keep a carrier group at sea for a week, all of these "problems" will disappear. (And Gee Whiz contractors won't need to sell us "The Next Great Idea".)
My .02 - Peregrino