Given my person choice, I would recommend it, but you do need to consider how active the wiki community may get. If we are going to be developing significant documentation and having that documentation be referenced from a number of 3rd party websites, I would strongly suggest MediaWiki. If all we are going to be doing is compiling FAQs and having it be more of a supplement to the forums, the existing software works out just fine.
Where I think MediaWiki would really come in handy would be in the area of page protection levels and the use of templates. Flagged revisions could also be useful in terms of specification documents, although other approaches could be used to accomplish the same basic task. It should also be noted that MediaWiki doesn't necessarily require anonymous user contributions by default, and such a feature can certainly be "turned off" if that is desired (such as is the current behavior for the existing wiki).