I am currently using Dyna Beads in the tires on my motorcycle with no issues or complaints. Dyna Beads are small ceramic beads, I'm guessing 1/32" in diameter that are poured into the mounted tire. Dyna Beads recommends 1-2 oz. in the front tire and 2-3 oz. in the rear for most motorcycles. Passenger cars or trucks will require more.
How well do they work? You've got me. The tires on my BMW are Michelin's which are very good tires. Motorcycle tires seem to be held to a higher standard than passenger car tires as far as quality and balance goes. I can't really verify that but it has always been my feeling. I've never had to add much weight to balance motorcycle tires unlike car tires that I've balanced.
One nice thing about the Dyna Beads is you can transfer them from your old tires to the new ones if you are careful not to spill them when you remove the old tire. At least that's what I do because I'm cheap!
Installing them through the valve stem is a pain. You have to pour them in REAL SLOW or they will back up and you have to tap the valve stem to get them to drop into the tire.
It is easier to pour them into the tire before you seat the beads on the rims.