I'm happy with them so far. I just did my first upper and lower assembly using mostly DTI parts. I read on the internet that they had some issues with their bolts in the past. But if you check out their forum in the industry section here, they said they now HP test and MPI each one of their bolts. I still went with an LMT bolt carrier group just for S&Gs (and it was only $10 more). Headspace between the DTI bbl and LMT bolt checked out great and the rest of their parts have worked out great. Only one slight issue. On their 16" heavy bbl, no chrome, it had some light surface rust on the chamber and a rust streak down the rifling sort of like the chamber was left wet. It cleaned out ok. It also had a raised burr inside the barrel from when they drilled the gas port, but I hear this is common for new barrels and shoots/cleans out just fine, which it did. The barrel is fully parked and it's got M4 cuts in the feed ramp. All of their flat top upper receivers have M4 feed ramps and T-marks as well. The hallmark on the upper indicates it was forged by Brass Aluminum Forging. I've only shot a hundred rounds through it so far, but every shot has been flawless.
I didn't need anything assembled in my order, and they had everything in stock, so it shipped in a couple of days.