Overall a good thread, well written.
To add our views to this, our site has three administrators. All have full access to the site, the adminCP, FTP and the SQL database. One of us deals mostly with the hosting and financial side of the site. Another deals with the graphics and the content of the site, along with the general user interaction as he's slightly less impulsive than me. I tend to deal with the coding side of things, making additions to the site and generally keeping it all together technically.
We all have complete trust in eachother.
We have a variety of forums, some of which are not displayed to guests, some of which are. This is more due to content within the forums, as opposed to enticing signup.
We have a few moderators across the forums, just to keep them tidy, but more importantly they are tasked with adding content to the forums and driving their respective areas. We give them pretty much complete creative control over their respective areas. The IT and electronics section is moderated by a guy who has an intense area in the subject. The vBookie forum with the betting threads is moderated by a fellow admin, as he has an intense interest in all forms of sport.
The adult material forum is moderated by a man. Because we're generally more perverted
We tend not to ban users, based purely because a lot of us, including the three admins, have came from a forum which was bought out and has had a great deal of restrictions imposed on it. We're all adults on our website, the youngest registered age is seventeen if I remember correctly, so we think that simply warning a user who oversteps the mark is the best way to proceed. It's working very well for us.
Just my two cents.