I bought one of the $1400 Mk3's from CDNN a couple years ago. It was the one that came with the Magpul PRS, 18" fluted WASP (nitride) barrel, and a 2-stage trigger. It was an extremely accurate gun, but had a number of problems that required it to be sent back to CMMG. It broke three bolt catches (maybe it was four, don't remember if the last one broke), the ledge for the charging handle latch on the upper wore down to the point the handle wouldn't stay latched (replaced under warranty), and they replaced the firing pin because the Geissele SD-E I installed had mushroomed the hell out of it (they said it was the trigger's fault, not me). The gun was also way overgassed so I installed a JP adjustable gas block. With the new gas block the gun was shooting smooth, soft, and accurately, but I had absolutely no confidence I wouldn't be replacing more parts or dealing with other issues in another 200 rounds so I ended up selling the gun and buying a POF instead.
Their tech support was great - I didn't pay for any of the fixes and they covered shipping both ways on all of it. I think they were having some issues with their early runs of 308 rifles and can't say if they have their issues worked out or not. I am not trying to bash the company or say they make a crappy product because everytime I spoke with them on the phone they were extremely helpful and willing to do what it took to take care of me. Unfortunately the rifle I had just had too many issues for me to feel good about keeping it.