I'm a fulltimer, and I had a Class C for a while. It only took me a year to figure out it wasn't right for me. I've had had a DP for about 3 years now and couldn't be happier. I didn't do any work on the Class C myself, so I won't compare the differences in doing work yourself. As for having the work done, yes, the DP is more expensive, and there are fewer places to have the work done. Having said that, I have never not been able to get the work done, it just took a little more planning.
I never say never, but I'll never go back to a gas coach. The comfort and quietness of a DP is significant to me. Having the storage available to bring nearly whatever I want is also a big benefit.
Fueling is easy, you just learn to find the truck stops. I prefer using the "Fuelbook" app, it only shows places with truck lanes.
All of the "house" stuff is the same.
I'm very happy with my DP, and don't regret the decision.
Good luck!