Our company has 2 diesel trucks that are used almost daily.
One is a '95 2wd extended cab Dodge with a 5spd transmission. It has 280K+ miles on it and I wouldn't hesitate to head out on an out of state road trip. The engine has been problem free for the most part besides replacing normal things like gaskets and belts. We haven't had one problem with the transmission. This truck is rarely driven without some sort of load and many times is pulling a gooseneck. The interior is junk. The radio has quit, the power windows have a mind of their own, the dash is cracked and the seats have multiple rips due to wearing the fabric so thin. Oh, and someone said in an earlier post that it will rust down in 10yrs.....this truck has no visible rust.
The other truck is an '03 Chevy 3/4 ton with the Duramax and Allison Transmission and 4 wheel drive. It had the injectors replaced, instrument cluster replaced and something else to do with fuel under warranty. Other than that, no engine or transmission problems. There was also an electronic 4X4 problem but it was a fairly easy and cheap fix. This is more of a runner truck but it does haul some loads and pull the same gooseneck trailer. All the electronics still work and the seats are wearing pretty good. It has 98K miles on it.
Performance wise, it's almost a wash. There isn't a big difference in fuel mileage under load, but the dually does handle big loads better. (That probably goes without saying) There is one hill around here that's about a mile long and is a good place to compare pulling loads. The Chevy will top the hill at about 10mph faster with the same load and maintaining the same speed up the hill. The Dodge is steady though and doesn't lose much speed throughout the hill.
I know comparing these two trucks really isn't a fair comparison considering the difference in age and classification. Also, I realize that both companies have changed even since '03. I have a buddy with a 2010 model 3/4 ton Chevy with the Duramax/Allison and he says he gets 10mpg loaded or unloaded and he's not real happy with that.
We had one experience with a Ford. I'll leave it at that....although my buddy has used and abused his and had great luck.