Well, I just returned from 2700 miles towing an enclosed trailer weighing about 7000 lbs. Lots of 80 mph on the interstate and I love my 6.4 PSD. And I love about everything else about the new truck. With only 3200 miles total on the truck its too early to know what problems might show up but it gets about the same mileage as my 04 6.0 got and the performance is far better. This engine is far more responsive than my 6.0 was. And on the hills in Wyoming I had a DMAX pass me on every down grade pulling an empty trailer but with the cruise set I went back by it on every upgrade. I'm hoping Ford had time to correct most of the early issues with the 6.4
With the problems I had with my 04 and the lack of support from Ford Motor Company I had swore I'd never own another. So far I'm glad I gave them another chance. Time and miles will tell.