If I restrict an article, for example, to just my subscribed Users or, if I want to restrict Client-specific information to just a particular Client, the title of the articles still appear in the ToC and Search Results.
This is a pretty major information/security leakage. Just the document title itself may give away proprietary or client-specific information. The Help Center really ought to be able to completely restrict visibility of an article to its Audience.
The current implementation is pretty insecure and insufficient.