While I totally love the multi admin and the ability to share access, the current implementation leaves some gaping security holes. Without getting too granular, I think the best implementation would be the primary admin invites delegated admins who have full access, except for adding/removing admins.
Today, if I invite someone to co-admin, they can then delete my access. Call me paranoid, but let them break everything else with the account, but adding/removing users should be restricted to the primary admin/account owner.
Ideally, we'd have a few levels of access, like we do in Enterprise. A read only user would be a great addition, or maybe a wireless admin who could update wireless passwords, but not change GX and GS settings.