Do you differenciate router context and business context?
What I mean here is that the router context (in the MVC pattern) would give us the dispatcher to use. When I mean context this way, it means "AJAX" or "Normal page" or "RSS".
Then you could have only one of these contextes.
The business context is more like "OG context" or "User role context" or "Site context" (site as in global database subset, some nodes only) these context can be more than once together (and don't even have to know themselves).
This is important to make this differenciation, you can only have one dispatcher, therefore you have only one "http query" context. But, as any module can do any business out there, the business contexts can coexist.
I think that if it isn't differenciated, you will experience problems, for implementation, and at runtime as well.
EDIT: The menu router, which is the MVC controller of Drupal could tell both the router context and one or more business context. An OG AJAX menu entry could tell the router to instanciate both.