I thought about this alot last night. The main problem I see is that the forum could get stale with just the same dozen or so people posting. This could be helped though, by members frequenting other boards and finding interesting posters to invite to join. This board and your recipe board is an avenue. So is the RC community if it starts attracting more people. I don't know what other boards members participate in, but it seems logical that we could "find" new members through parenting, weight loss boards, etc.
As for PI...well, if we do this I'm inviting her. Up to her if she decides to participate or not. I don't share her view that private and internet do not go together. Many sites on the internet are private to reduce trolling. I read blogs where the blog owner reads all the posts
first to prevent the kind of nastiness we see on Webmd. Totalitarian? Maybe, but I think it may be worth it. If we do private I'm going to look at it as an experiment. I'm still going to participate on R&C as well.