Ah I should have checked this before - line before:
2012-02-11T14:22:54+00:00 xx dovecot: director: Error: connect(/var/run/dovecot//auth-userdb) failed: Permission denied
This is because the director is running as user dovecot; but that file is owned root.root permissions 0600. What would you suggest doing? Setting that socket 0660 is the obvious solution but perhaps there is a more secure way you would recommend eg chown dovecot? I'm guessing this would also need updating in the documentation as afaik our setup should be pretty standard. Only other relevant piece of config:
service auth { user = dovecot client_limit = 15000 }
Also (perhaps this should be a new thread) but I'm not too sure the director service would work for us. I was doing some testing yesterday & discovered that when I restart a dovecot instance it doesn't have any persistence (eg resync the lookup table with the other directors or do a save/restore from disk) so you are basically starting from scratch again which would be very bad in our setup.
Mark