We were not looking for diesel to tow our 18 1/2 foot fiver, yes there was such a thing, but found a clean 05 Ram at a very good price so took the plunge. We have since upgraded the trailer, this beast doesn't break a sweat and gets very good mileage towing. I would not consider going back to gas.
Daily commuting is another story. It is not much better on fuel than a similar sized gasser and at the price of diesel it gets hard on the wallet. Wife uses it for shopping and medical appointments, certainly not the best thing for it, but it gets out and stretches it's legs on weekends. Things will change when I retire later this year.
Maintenance is not cheap, I only use quality filters, oil, and parts (no e-bay or wallyworld) but the trade off is less frequent servicing.
This thing has been almost completely trouble free. A rebuilt a/c pump was over three hundred and the wiper motor and linkage, has to be replaced as an assembly, was almost as much but after 9 years things like that can be expected.