I had exactly the same quandry....gas or diesel?? Towing 8,000 pounds put me right on the boarder between the two. I test drove several diesels and gassers of all brands. I knew it would be a Dodge, but which one?
Since I dont tow more than 4-6 times a year and generally less than 1000 miles, I thought the diesel would be overkill, and for almost $8000 I thought I could buy a lot of gas.
Opting for the Hemi was a good choice for me. Mostly flat land in IL lets the truck pull much better than the GMC hd 2500 I traded in. Went thru the Ozark mountains in Missouri and the hemi did a lot better than I would have ever thought. Certainly, it is not like a diesel, it does hear down some, but still maintained 9.4 mpg.
I doubt a cummins would have got "double" the mileage as some have stated....I had an 03 cummins that never got over 12 mpg towing similar weight.
Yep, the hemi does the job for me.....now, if I towed weekly, or towed 10,000 pounds, I would probably be driving a Cummins.....