Well its your call, but in defense of the 6.0 (i have an 04), the diesel magazines are beginning to tell that they are not as bad as many seem. In the last Diesel challenge there were 2 in the competition, both had around 1000HP and lots of torque. The magazines do not seem to be as skeptical on these being bad engines and with the right fixes say they will be very capable and dependable.
Take it to a reputable independent shop and have it checked out, codes taken if any, have a scan gauge hooked up and take for long test drive looking for issues. Better yet get someone to test drive with you that knows the engine/truck issues. Powerstroke.org and ford truck enthusiasts are really the sites to visit and ask your question. We are getting ready to take ours to colorado for grand daughters graduation in may, it is our travel vehicle of choice if not taking the rv vs the wifes honda or the hyundai towd.