I like the current implementation of private contests, but it could be improved. I can't think of a reason why other Contest Holders need to be able to view the details on a Private Contest. It's kept out of Google and kept away from people who aren't logged in. It seems the logical next step is to only allow those members who are registered as "Designers" to view the Private contests. Since the Contest Holders pay extra for it, the extra protection against potential competitors (other contest holders) would help.