I had a 2014 F350 shorted SRW. Pull a 14.5k "5th wheel" (now gooseneck) 35' toy hauler and a 22' bumper pull tilting deck trailer. 4k of trailer & 6k of tractor & implements on it, so usually 10k. 2.5k lbs of pin weight on the gooseneck, 800-1.4k on the Weighsafe bumper pull hitch depending on the load & ballance.I've been hauling both trailers this summer with a rental for reasons. Had a Ford dually for a couple months & a new Chevy dually this month. All diesels. I really can't tell a difference in stability dually vs single. The extra length & width is noticable in parking lots.
I'd assume the extra tires & stability show up with heavier loads. I'm likely to look at a long bed as a next truck for more room for camping junk, but won't be looking at a dually. Just extra cost & maintenance for my use case with no direct benefit.
The only thing I could think of would be loosing a tire on the rear & the extra getting me to a safe spot to change it.
Very different story if you are puling loads near the limit of the dualies, but my loads are always under the rating of the singles.