To get in the group you would have to get an invite. My reluctance to start one is that it would draw the already little intel away from the main sections of Z.
That would seem to be the primary drawback to the plan to me as well. If all the info is in the private area, it would make it hard for the newer customer members to get info. Moreover, the existence of the special invite only board would frustrate new customer members who could not immediately get invited. Almost a feeling that the "good" info is hidden and shared only by a clique of members, so why should a new member stick around.
It would also once again increase the distrust from dancers about the site. In the other threads, comments were made about dancers feeling there was less negativity and mileage chasing on the new boards, which is why some are starting to use it. A private customer only intel board would just increase the suspicions.
The final concern I'd have is that it would immediately have a big target on it. One of the discussions that's come up is the reason for not posting illicit info is that LE and club management might read it and act on it. A private, "no holds barred" customer board would immediately become the subject of more scrutiny.
I like the idea of a no holds barred sort of board, but its not feasible any more with the new model. The site has moved away from being an information exchange site and there's probably no going back.