I guess the one big thing in this discussion is for right now it only applies to the full floating axle group diesel in the semi floating axle group is limited to a smalll number of SUVs at this time (Dynatrac - Confidence to ExploreŽ
2014 Ford Super Duty | View Full Engine Specifications | Ford.com
General Motors Engine Guide | GM Authority
2014 Ram Heavy Duty: projections and predictions
the diesels will generally come with larger cooling systems, greater alternator capacity, available engine brakes, transmission rated for higher torque loads larger fuel tanks etc.
As for maintenance - it depends on how you use the vehicle for my diesel (I bought it with 100km on the clock it now has 320,000km) I do 15,000km oil changes(Rotella T6), 20,000km fuel filters, and 30-40,000km air filter 60,000km / year lots of highway use. For the gas vehicles 5,000 oil (Quaker State Dino), fuel filter is built into fuel pump in tank so will have to wait till pump goes, 25,000 air filter, 160,000km plugs lots of short runs mixed with infrequent towing. Trans and brake fluid every 2 years (gas/diesel) coolant 5 yrs (gas/diesel) -- So far the diesel has a running cost of $0.12/km vs. gas $0.35/km --note diesel has cost a lot less $ per litre than gas over the time period which is shown in the lower cost of ownership
for those looking to buy -- bottom line get the right tool for the job - alot of short runs or only occasional high load usage perhaps you are better off in a gas vehicle -- look at a diesel if you have frequent high load usage or longer highway runs you will recoup the higher outlay on the diesel pretty quick IMHO