I've used them for years....but they do have limitations. The buffing wheels you use on them have whats called a "pin hole" arbor hole. The down side is that in order to "hold" on the tapered spindle, without severe wobble, the buffing wheel must be fairly narrow in width... the maximum width I've ever been able to use is a 20 ply (layers of material that make up the buffing wheel) and not have the wheel wobble badly. I find them particularly useful for the thin "razor edge" buffs.
If you ever intend to stack buffing wheels....as I often do, they simply won't work.