I am planning on deploying Turnkey Twiki. I've been running Twiki for 5+ years.
I too ran into are a few issues:
1) When a user registers, Twiki fails to send the mail to the new user to finish the registration process. (I think it's an issue with configuration).
2) To fix this, one should run: www.yousite.com/cgi-bin/twiki/configure
It is asking for a user and password. I've tried all sorts of user password combinations with no luck. I found some info but I don't know exactly what the issue is. http://twiki.org/cgi-bin/view/Support/ConfigureAuthentication
3) If Turnkey Twiki was produced from Debian Twiki, it may have issues.
4) Would you consider FosWiki?