I've got a 2011 cummins, and you are correct, the 2012s did not have the DEF fluid. The 2500s & 3500s started that in '13.
With that said, I have had zero issues with mine. I deleted the DPF at 50k miles. Mileage went up 2-3 MPG better when I deleted, but when I put some 35's on the ground, the mileage went right back to stock numbers...13-14 while empty and when loaded it really depends what I'm pulling.
I deleted just because I wanted a little more power and to get rid of the DPF and EGR. I'm not going to tell you to delete or not delete. That's whatever you prefer, but if you do, don't skip the supporting mods as well. I've seen many guys that slap a tuner and delete kit, turn the power up a bunch and as soon as they start the truck they are pedal to the metal. That's a good way to pop your head gasket. Throw some head studs in it, let the engine warm up before hammering on it, and you'll be good to go. If you run around on higher power tunes, you better beef the tranny also.
A lot of the people that had the issues with their DPF going bad, weren't using their trucks like they should. They would tootle around town, sit and idle for long periods of time and not get the exhaust hot enough to burn out the build up...causing clogged dpfs. If you work the truck (sounds like you will be by pulling most of the time) you shouldn't have issues. Get ready for ball joints up front at around 120k-150k. If you take care of it, it'll take care of you.
I love my 2011 and wouldn't trade it straight across for a new ford or chevy.