A dually can haul more weight in the box, but can tow less. (legally) This due to the fact that the dually weighs more than a srw. It is right in the specs for the truck.
I know I am standing alone on this, but I am ok with that. I have towed alot, and not just with a dodge, I have had chevys and fords too. In fact as much as I hate to admit it, my duramax that I just got rid of was one of the best tow rigs I have ever had.
When I have towed with duallys I have found that I have gained nothing with stability (at least with a bumper pull) to be honest all my srw's have been the only 5th wheel tow beasts. I find with the duallys it costs me more to tow as I am repacing 4 tires at a time , and it seems to be more often. Also due to the fact that geneally duallys come with lower gear ratios (I realize not always but generally) that you dont get near as good of fuel mileage. I am quite sure that even if they had the same gearing that the srw will get better mileage (less weight and rolling resistance)
I have also snow mobiled alot in the mountains. We use snowmobile decks alot rather than trailers due to the bad roads. My freind runs a 2001 ford f350 drw, which had traded his f350 srw off on.. He liked the dually better for hauling the sleds (we would load 3 sleds on his deck) but he liked towing with his SRW better, and he towed basically every day He has a bobcat business screwing in screw piles. He had a big gooseneck trailer that he would carry his skidsteer and 16 to 20 piles and his attachments, over 20000 pounds.
This is my opinion based on many miles of driving,, so you can take it for what its worth I guess