i have two Knights SR-25s, one an actual MK11 mod0. they are awesome guns. however, as ammo is expensive, i don't have tens of thousands of rounds through them like my ARs.
I don't have any experience with the armalite flavor, but my experience with other people's DPMS 308s is mixed. seems like some run fine and others are problematic. go figure.
It's a dilemma though, as you can only buy used SR-25s and expect to pay 3x what a new DPMS will cost.
another consideration is customization. If I had a DPMS, i wouldn't hesitate to swap out the barrel and rails etc to get exactly what i wanted. The Knights guns are assembled so well (and are so valuable as is), I wouldn't dare change one of those parts myself. The only thing I've done to mine was put a magpul PRS stock on one. fortunately, the match triggers they come with are great, and the rails are great, etc.