shout boxes are for quick chit chat rly and forums better for questions and longer posts if there is a big following in the forums its allways good to have a chat box if you have say more than 5 people on at any 1 time .
I don't think a shoutbox would be used that much. I've rarely seen them be overly effective for forums. They work great for private things such as clans because they allow you to make quick announcements but a shoutbox just doesn't quite get enough use on a forum unless it's an extremely active forum.