We just purchased a 2014 2500 crew cab Duramax and traded in my 2010 2500 crew cab 6.0. Even though the truck was very expensive the wife and I are very pleased with the upgrade. Not only do we pull the hills in California with ease (I rarely exceed 55 MPH) I especially like the exhaust brake going down hills. My 6.0 gas truck got 9 MPH while towing now with the diesel we get 13-14 MPH.
We have the 373 gears in the rear end. One more plus that I feel is worth mentioning is the Allison transmission is near bullet proof, and is rated as one of the best on the road. Short of buying one of those Heavy duty sport chassis models this is the best value for us.