I don't think it's a good idea. It will take away from the forum activity, can be server intensive, and difficult to moderate.
Plus, questions and answers on the forum are archived and can be retrieved at a later date. Especially important for those who have the same questions and perform a query via a search engine (i.E. Google) will be linked to this forum to answer their questions, and can potentially draw them in to sign up which will make our ehealthforum community larger and more active.
I think a chat room would be a good idea. I understand what you mean about the ability for someone else to do a search, but the forum could still be kept. I've noticed that the main question I posted hasnt been answered yet, maybe with a chat room people would be more likely to give their opinions, ya know?