I don't think you can do much better than the M&P for the price. You can do much better for more money though. I prefer direct impingement for ARs rather than a piston conversion. If I want a piston gun, I'll get something designed with a piston from the ground up like an AK or a SCAR.
I think the amount of money you have to add to get a piston in an AR could be better spend on other more useful features. If you want to go top of line then yes they are going to be piston guns, so pistons are better, just most people don't shoot enough at one time or through the life of their rifle to benefit from it.
Edit: I was off with the pricing, if you're at the 15T/556 range of $1,200 up you can do better than the M&P too.
Last edited by tx787; 01-29-2011 at 21:39..