Yes, Tom, you're on the right track to be thinking about that. Seems like anything recorded (certainly including jam sessions including) are put into what essential amount to file sharing networks, and then "the cat is out of the bag".
Every professional needs an orientation whether to resist this (thus denying permission for the original recording to be made, or going clearly on record against file sharing). I don't know Jens' position on that, but mine is to take the passive route, and just not worry about stuff like people not buying my real records, or poor performances getting circulated. An artist now must realize that like it or not, almost anything played in public, or where there are people with recorders, that it might get around.
Since fighting for the alternative amounts to a losing battle, I've just accepted that there is a new reality in place, and not resist. I do like people showing enough consideration to ask whether I mind their recording me, with the understanding it will probably "get around". And when I think about it, if somehow this whole reality were something I could personally make the call on, I'm not even sure what I would say. There are some well-known good reasons why music should get around, regardless of the negatives mentioned above. In any case, it's really a moot point (anyone who recorded us could already be circulating them), so have at it. I think it is appropriate to ask Jens what you asked me, and see if he oks it too. Be prepared for any answer, since Jens is a deep thinker and that might lead anywhere!
Wishing you the best, Tom,