Looking for Wiki software with good access control and security

[James Lance]

So working off of the wiki theme here has anyone worked with twiki [www.twiki.org 
]?
I have some similar requirements where I need to have both internal  
and external users accessing the wiki.  I'd like to have certain parts  
of the wiki be access controlled.  For example, the systems group  
doesn't need to be readable by the world at large, but the KB for our  
app will be.

I downloaded and installed twiki a few weeks ago, but haven't gotten  
back to configuring it to our needs.

Has anyone worked with twiki?  Is it worth continuing on and getting  
twiki where I want it, or is dokuwiki going to be a better fit?

Thanks,

James