Are you suggesting limiting access to some areas of the forum?
If so one inevitably has the risk of creating first and second class citizens. This usually turns ugly.
If on the other hand you are talking about creating an advanced section, which is available to all, and you rely on the self-policing then there will probably be no problems with that, as most folk are sufficiently polite and considerate to stay away.
However, one might need a technologically more advance forum or skin(?) for the message board. (This one is quite limited in its capabilites compared to most I’ve seen).
I enjoy this site immensely, and the people and expertise, so I felt I had to comment but only to try and help out.