I had my 6.8 REM AR cerakoted FDE by a local guy here in KY, and I am very pleased with it. Matches the Magpul hardware and so far has held up - albeit I haven't shot it much. Have you seen the price of 6.8 lately? ? ? ? ?
The only drawback is that I had to turn everything over to the painter and wait, and wait, and wait some more.
I looked into cerakoting myself, but the need to bead-blast the aluminum was a non-starter as it would run about $1000 for a compressor large enough to drive even a small bead blast setup.
I am now looking into duracoating to see how that works, and I can do it myself. I had heard previously about the lack of durability, but since I don't shoot that much, I may just go with it. Besides, distressed paint jobs are all the rage right now . . . .
Did not know about the DIY cerakoting from Brownell's, will look into that as well. Duracoating also has a bake-on paint, but in a limited range of colors.
BTW, I actually painted a lower with Rustoleum FDE a while back, and it turned out well, considering I wasn't trying to be a pro at the painting. The finish appears hard, covered over the black nitrided surface (with multiple light coats) and does not obliterate any of the markings. YMMV