Re: Your choice, DPMS or AR10
OK...I don't get the DPMS magazine thing. The Gen2 Armalite mags are readily available, 5 rnd, 10 rnd, 15 rnd,20 rnd (not 19) and 25 rnd, and they are probably the best made, best functioning mag around, and only $30.00 ea. $27.50 if you buy ten. Armalite has a lifetime guarantee and their customer service is outstanding. Feature for feature they're a better rifle than the DPMS, which is why they're a little more expensive.
If you're talking about which is a better "pattern" to copy when it comes to building another 308 semi auto, then you have to consider parts availability like bolts, carriers, barrels and extensions, hand guards (some work with both AR and DPMS, some don't) LPK's (DPMS uses M15 take down/pivot pins) mags and so on, unless you plan on manufacturing all your own internals. Then it really doesn;t matter which rifle you pattern after, other than mags. Personally, I'd rather have a stack of AR mags (which I do). Mostly it comes down to cosmetics, and I really dislike the trigger guard designs on the DPMS rifles, which you're stuck with, but that's something that can be changed when building your own rifle.
Side by side, I think I'd depend more on an AR than a DPMS when things get rough, but again, when talking about a third party design, that pretty much goes out the window, especially for the purpose of this thread.