I had dualies and srws. The dualie tracks like on rails. If you pick up a nail or something you can still get to someplace to change it.
I had a 3/4 inch bolt in inner drivers side dual when I went to have them balanced. If it had been srw I would have noticed it right away. So you have to check them.
Handling and traction are reasons for drw. If you tow a sizeable boat it helps a lot to get it off a slimy launch ramp but you really need four wheel drive too.
Soft or muddy campgrounds dualie makes a big difference expecially if you have four wheel drive.