As you guys know from my posts (in this thread and others), I was completely satisfied with the 6.4L Hemi, but I'd never be such a fool to say it tows in the same league as a similar Cummins powered truck. Not possible. 400 to 500 lbs more torque from the Cummins (double or more!!), and the exhaust brake says the Cummins will be a much better choice when towing is the only parameter you judge it by.
The Hemi was a much better choice for me though. I bought new, so the purchase price was 10k lower here in Canada - and yes you get most of that back on resale, but I wasn't planning on selling at the time, and the Cummins plain sucked when used as a winter commuter never giving me really hot heat for the cab. It was just warming up when I arrived at work, which meant I froze all the way in (10 mile highway commute, and yes I plugged it in, had an oil pan heater, it was garaged, etc). I was also scared off by the EGR/DEF/DPF and all the added complexities the diesels are choked down with, and it just didn't fit my infrequent towing use needs.
Yes, we holiday for 3-4 weeks at a time, but I only tow 2-4 of those days - to get to the destination. Then we used the truck for sightseeing and hauling bikes and kayaks around. No need for a diesel, other than 2-4 days a year when the RV was actually hitched behind the truck. The other 360 days a year, the Hemi was the better choice for me. I'll trade the inferior towing performance offered by the Hemi (its a fact) to get heat in winter, cheaper oil changes, save 10k on the initial price, and not have to deal with the potential DPF/EGR/DEF issues.