thanks, because this question didn't get answered in march. nominated [again]
i'll keep this post with some tech, FWIW. i put them in my 31s in mid summer and have been great since. i already have them in my 34" LTBs but i haven't driven with them yet, so i'm not sure how well they'll work.
I've been running Airsoft pellets in 33" Mud Brutes on Spyderlocks for a year now with no issues. I don't drive the jeep daily but I do drive 1.5 hours and up to 70mph to go wheeling.
Only the beads required to counteract the imbalance will be used, the rest will distribute themselves evenly around the inside circumference of the tire. This is the beauty of the system.
After all this is a physics thing you know, I am sure that you can come up with a calulation to make it so that you can eliminate vibs at low to moderate; but you are going to have to balance the rim and the tire eventually. Unless its not used on street then you can do what ever really. For those in the US the DOT has standards on this I am sure, please do not put other peoples lives at risk by trying to balance your not street legal wheels or tires. Hey here is another alternative that I have seen with just about the same theory but safer since its not inside of the tire. http://www.centramatic.com/300.html
I just see the BB's being able to take on lateral movement that may develop into a bad thing.