Hi,
borgbackup developer here (borg is a fork of attic, with lots of fixes and some new features).
Just found your stuff, looks like we share some common goals / opinions about backup software, so it might be interesting to add borgbackup to your comparison list of backup tools.
If you want to have a look, easiest way is to use our binary build for testing.
https://github.com/borgbackup/borg/releases
Cheers, Thomas