I used Dynabeads in our former Airstream tires for 3 years before we sold it. I feel for the price it was worth it. If I were going to do it over again I would. If I could have afforded the Centramitics at the time that would have been my preferred choice though.
If you do go with the Dynabeads get one or two extra bags and extra valves and the installation bottle to keep with you in event of a tire issue on the road.
Mike
2006 Chevy 2500 4X4 crew cab Gasser
2013 Dutchmen Denali 311 BHS (Love the trailer HATE the manufacture!)