I have both a dpms and a RRA rifle both I love the RRA weighs so much more though, The dpms was a cheaper rifle sub 700 bucks if memory serves the RRA was over 1000 I know that for sure. The dpms had a few bad runs to start but that was due to the cheap crappy al. ones they came with, literally the whole mag broke apart while in the gun, the welds busted and the bottom came out and no I was abusing them, the LGS I got the rifle from was even surprised as I was on his range shooting the moment I purchased it. So I got swapped for magpul and never looked back.
I brought that all up to point out cheap mags can and will cause issues, I have seen it on everything you can think of at my Leo range. Our range master trys all sorts of things to see what should or could be used safely. He figured out a long time ago and it is very true pay for quality and it should never fail you. Same reason I dont suggest those cheap 25 dollar red dots for anything over a 22lr. Again this is all my opinion but I find my self shooting my DPMS more the RRA and it has not failed me as of yet from a actual gun related failure.
The one thing I do try to get all my friends to get is the 5.56 chamber since that is a higher pressure round then the standard 223, I feel it gives you some protection against a bad round from the factory or if you reload. Hope this rambling helps out.