Now see, this thread I can agree with. If you want to spend all that money on building a monster AR, perhaps you should use the DPMS as your shooter while you build your dream gun. Or later you may end up with a "mexicanized" Honda.
A good plan executed today is better than a perfect plan executed at some indefinite point in the future.
- General George Patton Jr
Your gun is a $700-ish gun. I don't say that with any intention of coming off as some insulting AR enthusiast brand-snob. It's probably a very good gun at that price. Mine absolutely was, and maybe someday I'll have another. I had a $700 Sportical that I upgraded with an M16 bolt, MOE furniture, and a Millet red dot. So I built it into an ultra reliable $950 light carbine. I have zero complaints about that gun. But I'd hesitate to dump much more money into such a platform, considering the alternative options once you get north of $1K.
If I'm going to place all my cards on the table, you're right. DPMS is not equivalent to a Honda Civic. It's more like a Hyundai. A good, practical, and reliable piece of equipment at its price, but with limited resale value and certainly not to be confused with higher end stuff. The difference between "in demand" and "big box store mediocrity" is dictated both by true quality parts that matter greatly in fuctional reliability, as well as popular brand names that offer little more than being trendy and expensive. But even the latter actually does matter if you ever decide to sell.
You can in fact build an excellent rifle on the most basic DPMS platform. This is undeniable. But you also can do a lot better (for yourself and your wallet) than your proposed project. You can build a similar, probably superior gun, for similar money, that will likely have a 50-100% greater resale value. And that's just plain better for you in every way.
There's nothing wrong with a basic DPMS. But if you attempt to turn one into a $2K gun, when you could build/upgrade a DD/LMT/BCM/etc at the same price...you lose. And believe it or not, I'd greatly prefer that you win. You don't have to buy the high end stuff. The cheap stuff is in fact pretty good. But it would be a foolish decision (regarding both quality and financial implications) to build expensive stuff around a cheaper platform in my opinion.
I think Sweeper's advice is sticky material. This information should be easily available since we see over and over new folks making this mistake.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together. You'll remember the quality of a gun long after you forget how much you paid for it.
US Army 1966-69, VFW Life Member, Retired Geek