IMHO the solution is to allow "discuss" subscribers to read "participants"
posting, but not to write on it.
This guarantees openness, and that decisions are not taken behind closed
doors (besides that a quick check on the history of the lists can show that
the only item of any relevance discussed on participants has been the
preparation of the draft report - and this is perfectly reasonable, because
I cannot understand how those who didn't participate in a meeting could help
in drafting the minutes).
In fact, all the relevant discussion has been done so far in the discuss
list.
What I confess being unable to judge is the technical complexity of putting
this in place, but I would be very surprised to learn that this can be more
of a few minutes work.
Roberto