If you are serious about buying a new diesel I would suggest doing it sooner than later. I can't speak for the others as I am a true cummins fan but Dodge in 2013 is putting the diesel exhaust fluid on ALL diesel trucks. Not a huge deal but I can guarantee you will have a higher re-sale on the the 2012 with out it and than a 2013 with it. Plus it will be a lot less head ache.
As far as if it is worth it or not I traded in my 2010 Hemi Crew Cab 1500 that I bought brand new on a 2006 Ram 2500 quad cab with the cummins and 150K on the ticker and haven't once regretted it! The gas engine did a great job but the cummins absolutely blows it out of the water! I just pulled the same camper I had with the hemi averaging 8mpg and the cummins averaged 16 into CO and 19 on the way home (down hill
) I didn't buy the diesel for fuel mileage, although it sure is a plus! I bought it for the comfort of driving! The heavier the truck the more control of the camper and I definitely feel much more in control of the rig with the cummins in front!
A 1/2 or 3/4 gasser will definitely do the trick but the diesel will be much more in control of the whole situation and for me safety is #1!