M. Ted, I don't think the recording medium makes much difference. Although casettes may not be as 'clean' as a mini-disk, they can still be cleaned up pretty well on a computer.

At most festivals I've attended, workshop leaders were pretty cool with people recording their sessions. I don't know that they'd be as much so if they knew someone was going to be distributing the recordings, though. If I made copies of a workshop (something I'd not ordinarily offer to do), I'd certainly want a commitment from any friends to whom I distributed those copies that the copies wouldn't take on a life of their own, being copied and recopied ad infinitum.

Certainly, circumspection is in order, but I don't think that's so just because it's CD's we're discussing rather than cassettes.