6.4 Hemi is a good gas truck. I'm at 65K miles over the last 4 years with mine, 3.73 gears. I tow an 11K 5th wheel somewhat infrequently. The truck is good not great. 98% of my complaints are tranny related. The gear spacing sucks and the programming is terrible. There is a mile gap between 1st and 2nd and even after overcoming that, the thing just hunts for gears and does REALLY stupid shifts all the time. Manually shifting takes care of most problems.... except the 1-2 gap, or course.
As a daily driver the truck is pretty close to perfect. MPG are good considering it's a 7000# truck. 12-13 in city/mixed driving, hwy can be 20 or even more if you stay below 60. Stop/go driving and speed REALLY drop the MPGs with this thing.
My 8000# TT felt a lot better with this truck. All that said, the 11,000# 5th wheel doesn't feel unsafe or anything. Suspension and brakes are great... it's just that dumb tranny!