Thanks for all the comments, as it gives me something to think about.
My main reason for wanting a diesel is for the better fuel economy, and the ease of going up and down hills. I find the sound of a gas engine screaming in second gear trying to climb a hill very stressful.
Right now we have a TT (X213), and we want to upgrade to a motorhome. Unfortunately, the last motorhome I had driven was a 1989 C-class with a 350, and that's what brings back bad memories of driving this thing. I'm sure things have improved greatly since then ! The idea of being able to do my own maintenance is definitely a bonus when it comes to the gas engines.
I'm starting to realize that any benefits of going to diesel will be outweighed by initial cost, as well as high maintenance costs.
My plan is to rent something similar to what we want before making our purchase.
Thanks for trying to steer me in the right direction !!