I was interested in this topic since I just put powder-coated wheels on my Wing. The powder coating threw the wheel balance off such that 20 grams of mass (about 0.7 ounces) had to be added to make the wheel balance. The best information I found on the topic of "Bead balancing" was here: http://www.innovativebalancing.com/index.html
Here's a neat video that demonstrates the principle and the physics involved; although I don't understand the latter - someone more capable than me will have to explain it. I just accept on faith that the principle and physics reliably work.
This is from a different manufacture. This demonstrates a balancer that is mounted to a wheel rather than beads installed into a wheel.
Motorcycle Consumer News published the results of testing ceramic beads (Dyna Beads) in their October 06 issue.
They used a new Honda rear tire assembly that was factory balanced with a 1.6 oz. weight. Rode the bike at high speed on a specific stretch of freeway before and after removing the weight. Removing the weight gave noticeably increased vibration.
They then poured the beads through the valve stem after removing the valve core (and noted it would be darn near impossable to install the beads in 90 degree valve stems). They ran the bike on the same stretch of freeway and said "the beaded tire felt heavier, with a stronger sense of gyro stability, but was noticeably less smooth running than when factory balanced, but just slightly better than with the original weights removed.
Their bottom line after putting the stuff to a real world test: "The theory is good, but the practice leaves something to be desired. Our advice: Go for a proper spin balance when you buy tires; it's more effective."
NOTE: I find Motorcycle Consumer News to be the best motorcycle magazine by far. They do not accept advertisements so all their reviews are, it seemes to me at least, real honest and straight forward. They have new bike tests, race reports, touring articles, monthly saftey articles and lots more. I look forward to it each month and seem to learn several things from each issue.