Actually, including the lower first gear behind the 6.6, lower axle gear of 4.10 option, the 6.6 has as much or more torque hitting the ground than you 05 D/A combo.
Other than passing fuel stations, the gas motor would be and is a good option.
If you're at higher elevations ie I've 5-6k alot, the diesel would be better. Only because it is a forced induction motor. Put a supercharger on it, elevation power loss is not an issue.
The newer gas motors are good power houses as compared to past motors. My 4.3 V6 with a 6sp auto pulls every but as hard or better than the 4bbl/TBI 454 BB gas motors I've had. The 6.6 has more HP/torque yet.
Other than the brain electron between my or your ears that diesels are better.....
These newer motors are good options.
Marty