Since this thread got bumped I'll talk about how it played out.
Caroline sent me a UPS label and they paid for shipping to get it back to them based solely on this thread. The aftermarket parts I installed we no issue for DD and their warranty, and were left installed when I sent it in. Majorly awesome.
Gun was at Daniel defense for 3 days, and shipped Fedex(odd since it went in UPS) back to. Total turn around time WITH memorial day, 14 days. Again majorly awesome.
Upon getting the return package, it was returned to me in the box i shipped it in (palmetto box), no free hard case like some reported, but that's more than ok. I opened the packing slip and to my disappointment there is no mention of repairs. No "inspected this, replaced that, this to spec". Literally no mention of anything at all other than "Warranty repair ticket xxxx". So that would be a slight criticism, I'd like details about what was done. Also, I didn't get a tracking number on the package return, it just showed up, so maybe in the future DD can work on getting tracking to folks so they can be sure to be home.
Upon inspecting the rifle, I was very happy. They replace the lower, new serial number, and they moved my Geissele SD-C and BAD=ASS safety to the new lower. My old lower was marked M4 Carbine and 223/5.56, the new one is marked DDM4 and multi cal, just an observation. The new lower also has a newer version of the single point sling attachment plate, much lower profile. The castle nut on the new lower was not staked like the old one, but I don't anticipate it being an issue. Most importantly, it reliably engages both Gen2 and Gen3 pmags.
Not sure if the old lower was out of spec or if they just said, "since he's worried its out of spec simply replace it". Thats why I wish repairs were listed, but honestly it doesn't matter. I got what i feel was OUTSTANDING SERVICE.
Daniel Defense, you just sold yourself a MK12, because after this experience, I'm more than confident in the way you do business to splurge on one!