I have a lot of experience with Diesel trucks, I'm on my 5th in the last 10 years. In my humble experience, backed up by owning 2 of them, the 6.0 PSD is a raging pile of horse dung. The 7.3 was great, the 6.4 is supposed to be better, but I haven't owned one of those. I switched to Cummins in 2007, but I only like the 5.9, the new Cummins (6.7) is smogged within an inch of it's life.
My Ultimate Dream Truck: 5.9 Cummins, with a Chev/GMC Allison behind it, in a Ford body/chassis.
FYI, I am looking at trading the Dodge for a 2008 6.4 Ford PSD today....I'll have an informed opinion shortly.
I owned a 2004 and a 2005 6.0 PSD, both of them left me standing on the side of the road more than once. Going back to Ford is a huge leap of faith.....