We often come across users we cannot find using their email and I have to download a report to search on the Federated ID.
What causes this is if a user changes territories (I work for a large multinational) and their account exists already exists but with diferenet email or when the users name is changed due to getting married. Being able to search for users by the Party ID would definately be a timesaver.
Also being able to search for a backup device would be handy as well from the same screen. Occationally we come across a machine that is associated with more than one user. This would be pretty much the only way to catch that