Lil Dog

Thats the only function of the Urea injection. It has nothing to do with the DPF regens directly. 4th injection is still used for cleaning the DPF but it should be less often if EGR is used less. Less Regens, better mileage. That and less EGR cycling makes combustion more efficient.

NCPADiesel

I wouldn't get so worked up about DEF, it's coming whether we like it or not...my 2011 Ford works just fine with it. It cost $9-12 a 2.5 gal jug depending on where you get it and it lasts ~5,000 miles for me. Not a real big cost at the amount of miles you get out of it. I get about 2 mpg better than my Cummins on the highway and about 1 mpg better towing the same trailer.

If the system is engineered properly and tested I wouldn't really worry about it. My buddies want me to delete the Ford, but at the way it performs I have no reason to at the cost of losing the warranty.