The mic concept defines one person as a performer, the rest as listeners. Not the message of your standard sixties folk club.

Have to disagree. That's exactly what clubs were like then. A lsitening audience, happy to join in when asked but not thinking of themselves as the show, happy to enjoy the work of those paid to entertain them. I've got photos to prove it, and tapes of live performances. I reckon there were over 800 clubs in the late 60's early 70's.