Thanks guys... I poked around a little bit and apparently the only time people have trouble with DPMS products is when they purchase a complete rifle or an upper, but the happy customers seem to greatly outweigh the unhappy ones.
That's all right because if I do this crazy project I'd most likely use this lower and a DPMS lower parts kit, and then whatever quality M4gery upper I come across at a reasonable price.
I'm going to go see if I can talk the seller down just a little bit.
Sigh, I really shouldn't start a project rifle.
But then again it looks like if you just follow the instructions on AR15.com and piece your own lower together, and then get a preassembled upper, you save some money and a lot of headache because the head spacing etc. is done for you.