Well, AMS is a singleton, so you would only have an attribute name across all packages using AMS. It would be interesting though to have the same attribute name in multiple instances of contacts (as an example) and have different values for the contact (object_id), depending on the contacts_package_id.
On the other hand, I like the beauty that you can share the same value of an attribute and maybe even do this across contacts package instances. I guess in this area some thought still needs to be put in.
As for belonging to which user, you could probably handle this with the permissions, but for the way contacts works, this is not needed (the permissions are granted on the group / ams_list level)
