I haven't log in for a long time, sorry about that. If you haven't done it yet, I'd still recommend it. I don't know about 2012's. There was no need for me to send in the cluster, it was just a flash. I bought the tune with a flash loader, that's the only way to do it. Then the only thing mechanical you need to do it is to get the dpf off and zip ties the left over connections. You'll need somebody to well you a missing exhaust pipe then. I've heard other people do it themselves buy gutting the inside of the dpf, but best to the section cutoff and new piece welded in. Other than that, there's nothing else to be done. The tune will take care of the EGR, the swirl motor, and the DPF, and the SCR.
Last year, I addressed the leaking oil in the back (oil cooler seal) it was a big job, so I had a mechanic do it. At same time, I capped off the EGR and and removed the swirl motor. No difference, since the tune already took care of that, but just cleaned out the engine bay.
Yes, with those addressed, the engine can be reliable. I've not had a problem since.
I hope this was still able to help you decide.