> In my opinion, it's not really worth it to back up books from your Kindle Use-case: I have bought books from other vendors, converted them to epub format, co

> In my opinion, it's not really worth it to back up books from your Kindle Use-case: I have bought books from other vendors, converted them to epub format, copied them via Calibre onto my Kindle reader. - I made lots of annotations in those books on my Kindle reader. Does it not make sense to back those books up?