I think, as long as it is a protected/moderated chat and people who are off-topic are not breaking up the conversation, it might work. Many new people find chat confusing or hard to follow, so it really would need to be kept on-topic to be helpful.
Another idea, which I don't know if it has been discussed before, would be to have the chat logs made available on the boards afterwards, so that people who were not there could have the opportunity to see what was discussed and ask questions later.