Multisite: Partial Super Admin Users?

We need a sub-blog admin to be able to edit users profiles (knowing full well the edits will affect the whole network). For business reasons, we must have this function. Yet for technical reasons, the person who would be doing the editing has no reason to have all of the Super Admin capabilities. We really don’t want to grant them power to break everything if they click a wrong thing.

Does anyone know a proper way (i.e. that would survive future updates) that we can create a “partial super admin user”? Someone who has power to edit users, but who is not all-powerful over the entire network?