I'm starting to think of this more as a "to trailer or not to trailer" thing.
What I mean is this:
Folks get a F350 with a diesel just because. Because you can. Because they want a diesel. Because they get 4 extra MPG on the interstate. Because it puts more hair on your chest. Whatever.
If this is why you want a diesel, it will NEVER work out financially. The rest of the truck will eat itself long before the engine does, the fuel is more expensive (now), it's heavier, parts are more expensive, blah, blah, blah.
All that's true UNTIL you're pulling a 10k# trailer up a mountainside. Then you'd give your left arm AND leg for a diesel. My Dad get's the same mileage pulling his huge 5th wheel with his Dodge 3500 Dually Diesel as I do pulling my little 5,000# bumperpull camper with my Expedition. And he could walk away from me in the mountains.
If you don't tow, I don't know why you'd ever want a diesel, honestly. But if you tow more than a few thousand miles a year, I bet you'd want one very much...and would benefit from it. Not in longevity, necessarily, but in comfort while towing. Mash the pedal and it goes. Mash my pedal and it thinks about it, downshifts, winds up to 4,000 RPM, starts to get a head of steam, then starts going somewhere. Big difference.
That's my philosophy/observation.