If you look at jus2shy's spreadsheet, you will see that the diesel produces 43% more power than the Hemi at 1500 RPM, 41% more at 1750 RPM and 33% more at 2000 RPM. This is the normal RPM range for highway driving so that during the great majority of its highway towing, the diesel will be more able to stay in its OD ratios pulling more weight than the hemi. Also, while it can't accelerate as fast as the Hemi, you won't need to rev the snot out of to get the load moving. When it needs more power to the wheels, it has six non OD ratios to chose from to get it up the hill including a 4.7:1 first gear. It just won't get up the hill as fast as the Hemi.
The diesel has the same tow rating as the Hemi for a reason in spite of it being down on peak HP. The beauty of having more gears works for both of them.