I am planning to full-time in a few more years and have read numerous gas versus diesel threads. I think the first question to be answered must be how you intend to use the motorhome. I want to do a big trip all through Canada and Alaska.
After that I want to stay primarily in federal and state public lands, moving every other week at the most frequent, and not going that far. I would be surprised to see 10,000 miles annually after the big trip.
If I stay healthy and live long enough to wear a gas engine out then it will be my pleasure and delight to get another. Whoo-Hoo!!!!
Once the question of use is answered we can evaluate the meaningful differences in the things that matter to us.