Before switching to multisite and running into headaches, I'd like to ask about users across various sites. Basically...is WP as a network appropriate for web designers to manage many client sites under a single WP install?
Do users on one site automatically have a role on all the other sites?
Say there are two blogs (of totally separate customers) and a visitor registers on both to comment -- using the same username/email/password combination. Will it create two totally separate users, or will they collide/find out they are already registered when they try to register on the second site?
Is WP multisite intended to let designers manage a network of totally separate customer sites as completely independent sites, but with a single install (like Drupal does)? Or, is it more intended to allow us to create a network of "related" sites and subblogs?