I had an '11 crew cab with the 4.7 and I just traded it in for a 2012 crew cab with the Hemi. I do a lot of camping and I tow a 5500 lb travel trailer through the mountains in Alberta and BC and the 4.7 just didn't have the power through the mountains. My mileage was between 11-13 mpg towing on the highway and I could get it up to 22-23 mpg highway not towing. Towing this trailer on the prairies out here wasn't a problem.
I will be towing my trailer with my new truck for the first time this Friday and am pretty excited to feel the difference in power.