Re: Group Forums
In my personal opinion, it will dilute the main forums and divert the traffic. Most of the groups I have seen so far serve no good purpose (i.e. no discussion) and a lot of members (including me) don't bother going back to visit those groups any way. It's more for popularity "I am a member of so many groups".
However, if you were still to go ahead and implement what you mentioned, I think that's a good way of doing it. Make the group owner the moderator and make those mini forums visible to those group members only.