I've owned my truck since 9/11/10 and have yet to have the first "issue with all the emissions stuff. " It's never been back to the dealer for anything other than routine service, never had a problem message pop up in the EVIC, never a check engine light. As far as I'm concerned, all the emissions stuff has been pretty transparent to me.
According to Ram/Cummins, the switch to DEF is supposed to improve fuel consumption by around 10%, IIRC. If that's the case, my truck that gets 10-10. 5 MPG towing and 16-17 MPG running empty on the Interstate would get 11 or so MPG towing and 18. 7 MPG absolute best running empty. That's noticeable, I suppose, but one has to weigh that against the DEF hassle. DEF or no DEF - neither one is a deal-breaker for me.
Rusty