Originally Posted by dwanthny
It looks like we agree.
Yes. I posted some disadvantages of using Save to Disk as a backup strategy, but there are advantages that I didn't mention (although others did). The principal one is the distributed nature of the metadata storage. Each book stores its own little bit of Calibre-compatible metadata with the book formats. That makes it easy to bring the book back in to Calibre in someone else's Calibre library, or recreate your library from a subset of books.