If you think about it though, there would be less management in the long run if you have multiple instances of the Documents Module on a page, each with appropriate permissions for the roles.  If the permissions are done right, you will still have the same effect.  Of course, there would be a little extra work up front, but afterwards, management should be less time consuming.  And...  It is free.  I know how difficult it can sometimes be to purchase certain things when working for a school system.