Don't forget about the tranny. I went diesel, so I don't know much about the tranny in the 6.0. I went with the diesel because of the Allison transmission.
If you blow a tranny you will eat up the cost difference pretty quick.
My previous truck lost the tranny twice ... hence ... go with the Allison. That was the tipping point for me.
Diesel = more power and torque = tougher transmission