I have had gas engine units for 10 years, have analyzed the same gas vs diesel question when I purchased. My thoughts are:
1.Rear radiator in diesels leads to overheating problems---if not properly manintained.
2. Fuel/filter problems lead to many diesel engine problems.
3. Accessory items seem to fail on diesels, believe the basic engine is long life, but some of the many switches, etc. seem to fail or cause problems.
4. With a new gas unit I could pay cash, but a new diesel costs quite a bit more and I did not want to borrow $$$$$.
5. Maintenance costs (parts and labor) seem higher. Believe with a gas engine you are dealing with automotive/individual type of charges vs industrial/corporate type of charges with a diesel.
Now, if you want a big (over 38 foot), heavy, powerful, smooth riding coach, diesel is the only way to go. Also I now only put on about 8,000 miles a year and half time it, so the justification of a diesel is very difficult. Coach is sitting and being lived in most of the time.
Selection depends on your own situation, use and thoughts.