We use Edit Flow, and have hosted over 200 individual authors. It's meaty, but it's easy to pick and choose which features you need. It's not at all cumbersome on the back end, which is nice, and pretty rare for a plugin that does as much as EF. We send all our posts through a line of people, copy editors, fact checkers, formatting wizards, and the art director, and using Edit Flow's custom post statuses keep us out of each other's hair. Plus, it allows us to leave feedback for each other privately, or leave each other terrible puns no one else is subjected to, as the case may be. I use it in combination with a few other plugins to limit author access to the good parts of the dashboard, and to keep authors out of posts once the editing team has started in on them. Two authors are a lot easier to keep track of than 200, so it may be too much car for your site at the moment, but Edit Flow would make it easier to expand your writing crew in the future, should you chose to do so. Edit Flow is one of maybe five plugins I'm excited enough about to insist other people use. I'm not usually a rah-rah sort of gal about anything, but Edit Flow is made of unicorn magic.