I too carry a heavy TC. I've been having this same debate lately. Many of the posts in this thread assume you will be hauling/towing heavy and need the torque of a diesel. If all you'll have is a TC that's like towing a 5,000 pound trailer. Something nearly any V6 1500 truck could do. So, power wise the diesel is completely unnecessary.
My current truck is an '05 Duramax and it has been great. However, the extra $8,000 or whatever it is, combined with more expensive fuel, has me strongly considering a gas engine for the next truck.
The compression braking of a gas engine is very good, probably comparable to some diesels with an exhaust brake. Anyone who is "smelling burning brake pads" doesn't know how to downshift.
In running diesel construction equipment, driving diesel pick-ups, and working for a while as a truck driver I've never had a water in the fuel problem. To me that's a non-issue. Just buy fuel at reliable places and change your filters regularly.
In looking on the Dodge site I think they lower the GVWR for the gas powered dually vs. the diesel one. I can't find that for sure but there are clues. Since it appears to be identical in every way except for the engine I don't know why they would do this. It's one more example of the wacky ways manufacturers sometimes change GVWR. Since I don't worry about those but instead go by the trucking industry standard practice of looking at axle and tire weights so the reduced rating wouldn't bother me.
I think, if you're just going to haul a TC then the gas engine is probably a less costly way to get a truck very capable of the task.