Frank,
The dealer that I worked for previously had a mix of GM and Ford trucks...about 5 total. All the trucks were run every day, hard. They had the best service from the DMax/Allison trucks. I remember one truck that had about 45k on it and only ever got two oil changes..nothing else.
The older/1st D Maxes had injector troubles... but that's a small drop in the bucket compared to the early 6.0 PSD.
My D Max is great. You know you guys can test it out any time...
I have a Gas Ford 250 as a work truck. The engine is junk. The truck itself isn't bad, but it doesn't handle or ride anywhere near as well as the chevy does. Both are 9200lb trucks.
The Allison Tranny is FAR better than the trans in the Ford....