For about four years now I have been running the Dynabeads in my personal motorcycles and Avalanche. In the fleet vehicles I have been using the heavy Airsoft pellets. All together about 20 rigs running dynamic balancing media.
They work best in a tall skinny tire. Results in the wider low profile tires have not been as good. The majority of the fleet runs 235/85-16 tires. Out of all the tires balanced I have only had one driver who complained. I went back to weights on his Tahoe. The rest are reporting smooth as butter. I am seeing improved mileage from the tires and maybe it is wishful thinking, but tread wear seems to be more even.
The Airsoft pellets do make noise when stopping as they "rain" onto the wheel. This is more noticeable on the alloy wheels. It takes a little getting used to.
I would avoid the copper coated BB route. Some amount of moisture is inevitable. The rust from dinged up BB would be a bit of a mess. I have dismounted tires with 50K and recovered the media. There is some light dust from the Airsoft pellets. The heavier black pellets do better than the next step lower weight white pellets. Overall the deterioration is minimal. I reused them. I may have some closing in on 100k of use now.
The ceramic Dynabeads have shown no deterioration.
How do I recover them. On the bike with a tube, I reuse the tube , or sacrifice it and install a new one. For the tires running Dynabeads a ladies nylon on the inlet of the shop vac , right where the hose enters the vacuum. For the Airsoft pellets a "rattle can" / paint can lid and scoop them up.
I for one, have found the benefits of dynamic balancing and will stick with it. It does work and works well. That said, I will not be using them in the rear tires of my quarter mile rig, nor the wide low profile tires of my wife's daily driver. I think they have their place.