When we first started towing an RV in 2004, my first 3/4 ton was a Ram cummins for pulling our new 5th wheel....everyone said I needed a diesel. After a year, I traded it for a v10 Ford gas truck and probably won't own another diesel....just too much hassle for me.
First, I froze to death in the winter due to no heat in the cab. A guy told me to "plug it in"....sure enough I found a plug under the hood and started plugging it in at night and it was toasty warm in the morning. Then, a few times I forgot to unplug it....back out of the garage and the darn extension cord was behind my tool box, and over she came....dammitttt.....more than once.
Then I opted to change the oil....put a ten quart pan under the truck and didn't realize it held 12 quarts of oil....never did get all the oil stains off of the garage floor.\!!!!!
Every time I changed the oil filter I took a bath in dirty oil....
My wife complained daily about the diesel fumes going into the house from the garage....ugh
Almost ran out of fuel twice because I couldn't find a station that sold diesel fuel....ouch
Everyone told me I'd get 20+mpg...never happened. THe best I ever got unloaded was 16-17 and towing 9500 pounds was 11 mpg.
I found the maintenance to be a lot more than I ever would have thought...I do all of my own work, but I found it to be a pain.
SO, I traded for a V10 F250 and put in gas, changed the oil, did not have to plug it in, no more fumes, did not run out of fuel, and got 9 mpg towing and gas was about $.75 cheaper per gallon than diesel at that time.
Having said all of that, I currently pull a 8000 pound fifth wheel with a Ram 6.4 gas motor, and it does well. BUT, if I was pulling any more than that, I would buy another diesel in a heart beat.
You cannot beat them for pulling power, if you need them. We pulled a buddy's 14,000 pound 5th wheel from Arizona to Illinois last summer with his F250 powerstroke....no gas motor would had done that job.
Moral is that if you NEED a diesel, buy one...but be sure you need it. My nephew bought one a few years ago because he thought they were cool....That lasted about 6 months and he lost his butt on a trade in.....
The cost of the diesel motor is $6-$8,000....you need to keep it a long while to get your value out of it...