I have a 07 5.7 DC limited which I bought in 2010 with 35K on the odo and I love it. I just passed 85,000 miles with no issues. I use it as a daily driver and to tow my FJ40. I tow back and forth to Moab twice per year, around the front range 4 to 5 times a year and just got back from towing to and from Ouray. The truck will tow as hard as you want it to and it will maintain 75 mph though the tunnel.
MPG empty: 14-15 around town and 20 hwy.
MPG towing 7,000 lbs 9-11.
Only compliant is that is a bit bouncy on concrete roads when empty, but it is a truck.
I would recommend the truck