Back Up Root for PureOS Byzantium

I have experienced an update to PureOS Byzantium in the past that prevented my computer from successfully booting to the desktop. To prevent that from happening again, I’ve started backing up my system partition to a separate disk before installing any updates. I use rdiff-backup to back up / and exclude /boot, /dev, /lost+found, /media, /mnt, /proc, /run, /sys, and /tmp.

I have not yet needed to restore from a botched update since reinstalling PureOS. I just want to confirm whether this approach would work. To restore my system following a broken update, I would simply boot to a LiveUSB, delete the relevant folders from my root partition, and copy+paste the latest working versions of those folders from my backup.