Yep, it’s going to be squeaky clean and de-cruftified. I’ll probably install to a new SD card and then transfer what I need.
If you rename one of your backups that predates a significant update/upgrade, my script will (should!) ignore it when counting previous backups and checking dates. For example I have just renamed 2017-06-02 to 2017-06-02last17.2 after ‘inadvertently’ upgrading to 17.3 from the staging repo on 3 June.