At the risk of sounding like a used car salesman - we have both the glass beads and the stainless steel. I'm attempting to update my website, and the info for the stainless is on there. If anyone is interested in either of them, you can PM me and I'll send the info to you directly.
I'm another who uses the copper coated steel shot, and have no qualms about doing so. They are encased in a muslin pillow, surrounded by polyfill, and then encased in a hide lined with muslin. The chances of that changing over time has got to be very, very limited. Although I'm willing to look for alternatives if something has come to the forefront screaming a change in materials.
And I'm with Shelli here, sometimes I'm willing to take sacrifices if it means achieving a certain feel or goal