I have recently replaced the Bilsteins on my rig with Koni's. I put the Koni FSD's on the front and my RV mechanic is installing the adjustable Koni's on the rears this week.
My rig had 46,000 miles so I am not sure the Bilsteins were worn out but I was having more side-to-side pitching than before. When I drove my rig to the shop this past Monday, I could definitely notice improvement in the handling and ride quality of the rig (just from the Koni's I had installed on the front). The ride is softer but handling seems improved. The coach seems to glide more softly over rough places in the road that would jar the rig previously with the Bilsteins.
At this point, I would say the ride is more civilized than before. I am anxious to see how the coach does with the rear Koni's installed.
2007 Country Coach Allure Siskiyou Summit, sold/traded Nov. 2018.
2019 Grand Designs 384GK-R 5th wheel. Glen Allen, VA