I too wonder if I should have gone with the 6.7. I bought the 6.2 with the intent of conventional towing around 10k. I have since decided on a Cougar toy hauler 5th wheel that has a gross rating about 12.3k. I believe my overall loaded weight on the truck will be in the 12-12.5k range. I am thinking around 2k pin weight.
With the 3.73, Michelin E rated tires and perhaps some beefing up of the suspension, I am asking myself if mine will be enough truck for that load.