I've been happy with my Koni FSDs; they seem to work as advertised. I do have Ride-Rite air helper springs in the back that help a lot with the stiffness of the suspension there (aiding in controlling sway and bouncing). That's not to suggest the motorhome rides like a luxury car.
If you're a DIY type, replacing the rear shocks in the Ford E-series chassis is a piece of cake. Replacing the front ones is considerably less convenient; access to the top nut for the front shocks is difficult. I found a flex-head ratcheting box-end wrench the best tool for the job, or perhaps more accurately the least terrible tool.
If you're getting bumping and clunking in the steering wheel, also check the tie rod ends for looseness and the radius arm bushings.