Generally speaking, the 6.4 Powerstroke is marginally better than the POS Powerstroke 6.0. Many of the experienced Ford techs actually like a "bulletproofed" 6.0 better than the 6.4. Posting trouble free performance with only 25000 miles on the truck is basically meaningless...the 6.4 has had radiator and water pump issues that were very expensive to repair...It is a strong performer but like Donn wrote: "Decent truck if taken care of. The 6.4 has a less than stellar record and is generally noted as a fuel hog. There are better trucks out there for sure. Remember it was a IH motor at the end of the Ford/IH relationship.".
GM and Ram have a much better track record with their DuraMax and Cummins engines...
Regards
