Hi guys:
The Safe-T-Steer cost about $600, installed by Camping World. It cured my side to side sway, road wobble, and blow by wobble from passing semis.
It will not cure a 'rocking' motion from pulling out of the driveway, but does stop the tracking caused by ruts in the road left by overloaded semis.
It also stopped my coach from being blown all over the road by the wind.
Anything to improve safety is money well spent, IMHO.