Yes - I bought a Del-Ton upper assembly for my first AR build. For me, they were great. Very responsive to my numerous questions, fast shipment, and best of all, the upper assembly I bought has worked flawlessly.
I'm working on another project and would use them for it as well - but I'm looking for some specific things that I haven't seen in their inventory (e.g., high end barrel 1:7 stainless, etc).
I helped a friend build an M4 from one of the del-ton kits. Upgraded to the YHM FF rail and a phantom flash suppressor and a SOCOM stock. The gun is beautiful. We found out that we had received the wrong buffer spring. Del-ton really earned my business in the future by sending a replacement spring PDQ no hassles, totally customer oriented. Very professional. I am preparing to set up a group buy for the officers in my county and plan on using Del-Ton for the uppers.