File System Archiving is now part of the "EV Archiving" bundle. its licensed based on front end capacity which means the size of the data before its archived. the license bundle includes File Servers, SharePoint, SMTP Archiving, and IMAP access for internet mail archives. the capacity based license has no restriction on number of users.
you might want to also look at File System Archiving ias part of a different bundle called File Governance which includes File System Archiving and Symantec Data Insight. on a side note, as a partner, you should be able to get the Licensing Guide which has all this information for you.
