Hi, Brian!
Shadowing has the potential to let a user see student grades and student work, as well as student enrollment in the Roster and, by implication, parent-child relationships. In other words, it can give the user access to more than just the Pages section of the class.
Down the road, we're more likely to try to meet this need for collaboration and team teaching through some kind of "Public to Domain" or "Public to Organization" option that would make the Pages section of a class visible to all users (or all users with a certain Role) in the applicable Domain or Organization. At the moment, we're a little wary of making it easier to assign Permissions in bulk if that need can be met through a more secure approach.
Would a "Public to Domain" or a "Public to Organization" option meet the need you're describing? If not, let me know!
Cheers,
Justin