[Quoth]

I'm sorry I didn't make it clear that SideloadedMode=true was a setting in the configuration file. Signing out is a bit like deregistering a Kindle.
Signing in only affects SideloadedMode if it is in the settings, in which case it's set to false.

If you are signed in, enabling sideloaded mode preserves all settings and only makes it seem as if you not signed in as well as changeing the User Interface. I'd not imagined anyone would think I was suggesting actually signing out.

Using Calibre to separately backup database (can be done just by copying) and also using added columns for reading status & position is a good idea.

I always use Calibre to read the Annotations etc for a book when I finish it and copy/paste to text file, though it's possible to store per book annotations in Calibre I don't.

Never signin or signout without a backup.