If I towed something heavy I would definitely have a PSD Excursion, but I don't have anything over 5,000 lbs to tow so I bought what I could use. Anything more than a gas V8 was overkill for my needs.
FWIW I wouldn't touch a 6.0 PSD, it would have to be a 7.3 PSD or a Cummins. I don't know...