I have to admit that I've never really seen sway as problem while driving, even in the windiest storms and conditions. However, turning into driveways would definitely cause the rig to rock back and forth a time or two. My wife wasn't a big fan of that part.
I saw that Roadmaster had introduced a new 1.5" diameter rear auxiliary sway bar that retains the factory bar in back. This one mounts in front of the drive axle and differential and has bends in it to clear the drive shaft. My wife decided to get me one installed as a Christmas gift.
Luckily Roadmaster is just across the river from where I live and they were able to get me an installation appointment (note, demand is so high on adding these to Sprinter-based RVs they are backed up by about 10 weeks at the time of this post in terms of manufacturing them). I was out of the shop in about 2 and a half hours.
The results? No more rocking back and forth as I turn into or go out of driveways. Yay!!! I guess I didn't really realize how much sway there had been before until I felt the after installation experience. And, admittedly, whereas I didn't think I really had any sway issues under normal driving I really can tell the rig was more firmly planted now. Downside? The only thing I noticed was that the ride isn't as smooth as it was given the rear suspension doesn't absorb all the bumps. Wasn't bad though and I don't regret doing it. I may be retightening some screws more often though given more road vibrations make it to the back of the rig.
Rear Aux sway bar 1 1/2 diameter retains factory bar.