My M15A2C is circa 2005 and has been a fantastic carbine. I've never had a malfunction that wasn't attributable to crappy/damaged magazine that choked my other ARs. Accuracy is perfectly acceptable for what it is, about 1.2 MOA with good ammo, a bit over 1.5 with M193 or M855. No problems with P mags or other polymer magazines seating, feeding & dropping free.
It has also been reliable with every suppressor I've screwed onto it, even though it still has the stock front sight base and stock size gas port.
Armalite uses (or at least used to use) a patented, proprietary bolt that has a reduced lug opposite the extractor. This actually makes the bolt less likely to break lugs than a standard one with all 7 lugs engaging, as it causes the 6 lugs to share the load more equally, while a 7 lug bolt will stress the lugs on either side of the extractor more.