The time I tried Import/Export, it did a wonderful job of making a complete copy of my active (that that show on the Quick Switch List) set of Libraries.
Import allows you to select a sub-set of that list, but not inside a Library.
For the average Joe, it is a great way to create a basic backup of all the pieces without needing to know where things are.
For my routine (sorta Daily
), I keep that Mirror copy on another system with
Free File Sync (The copy is fully functional, but I never use it there for any thing other than to pull a book to fix a oops! in the regular use Library)