Question though. Will you have the same tags set when you log in that you had when you logged off or will it always default to your basic single user tag?
With the level of detail and control that this allows, players will really have to be aware of what tags they have set when doing things, especially if they belong to even a single organization, much less multiple ones! Imagine if you created an incredible new design but forgot what tags you were under at that point. All of a sudden the organization that you are only somewhat involved in has control of your design instead of you. Or that secondary group that you joined for fun gets control of something that was meant for your main organization, and all because you had the wrong tag assigned at the time!
I think the best way of handling this would be to make it an option so each player can choose what happens when they log in. They could pick either themselves, one specific organization or the same organization as when they logged out. That would be determine who they represented each time they logged in, until they changed the option.