I had thought that the new piston ar's that are so fashionable right now were somewhat of a gimmick. Yes, the principle of not pooping where one eats* does make sense. I also thought that the current platform was working pretty well, but apparently this is disputed by some. I don't particularly feel the need to upgrade, as I don't live in the Iraqi desert, and I ain't got the money anyway.
* This refers to the AR's gas impingement system which routes propellant gases and therefore residue back into the action as a means to operate it.
H/T Concerned American