I've never seen the Dyna Beads. The Counteract Beads are glass about the size of a BB. Originally they come in pre measured plastic bags that we throw in the tire and the plastic disintegrates in no time. I have a dedicated Shop Vac for sucking them out when we take a tire out of service and we store them in the vacuum to reuse. We reuse them until we snag a sidewall and lose them. I don't keep the vacuum locked and this is how the drivers get their hands on them for personal use. I kinda figure they wouldn't be snitching them if they weren't doing some good. Counteract's main market is class 8 vehicles, but their web site lists 1/2 tonne vehicles.
http://www.counteractbalancing.com/counteract/index.php I learned about them in Europe about the mid 90's.
