I haven't towed with one but I have heard they do very well. If I were a hobby racer that didn't pull through the mountains I would go gas motor. The diesel stuff has gotten so expensive for out of warranty repairs I just couldn't risk it on my dime. Say at 200,000 miles you kick the rods out of a 6.4(unlikely). Then say at 200,000 miles your common rail diesel needs injectors(likely). I bet the long block for the 6.4 cost less than the injector job in the diesel.

You do have a good truck sitting there with your 06, but everyone gets the itch for a new truck! You should be able to sell it at a premium cost.