Funny, this is the exact same problem I see with google+.
We're using hangouts to do some cross-continent roleplaying sessions, and g+ is a natural fit for having a discussion group/notes -- unfortunately it has horrible mail notifications (you get a notification, but not the content of new comments) -- and is pretty buggy (with posts randomly disappearing when you're accessing g+ across devices).
Having a few parallels discussions is almost hopeless -- and this is just within one "community". I couldn't imagine using it for anything involving more than a handful of people.