Great info on the thread so far and let me pile on.
I tow an 8500# (loaded weight) TT and came from an 06 Duramax to the 6.4 Hemi. Towing wise the two trucks are surprisingly close. I'd have to admit the diesel does take the gasser by a hair but for my weight it's really not a huge margin.
As a daily driver the new truck takes the prize by a HUGE margin. The rear coil springs and overall suspension system are far superior to the old truck. To be fair the new truck is 8 years newer and there is a large improvement in vehicles as a whole so I don't mean to dog on the 2006. It's just a fact of life that a 2014 of similar ability of a 2006 is going to just feel better.
Bottom line is the 6.4 Hemi is more than capable of what you need and the 11 years forward in technology will totally amaze you. I say go for it.