Upgrade MainPC (and BedroomPC) to Debian [3]

This is really just a quick followup to two of my four PCs replacing Xubuntu with Debian running Xfce desktop. It’s interesting that I tried out Debian a few times in the past and never liked it that much, maybe using the familiar Xfce desktop has helped but it is far more likely the case that my increased familiarity with Linux has been the determining factor. In both cases the installation took more work than Xubuntu but I am quite confident of being able to overcome any challenge with Debian by now, it has a well deserved reputation as the king of Linux distros due to its very long and continuous development over more than 20 years, stability and widespread adoption and support in the OSS community. 
I still have one PC running Xubuntu and there is absolutely no rush to change it over. Like the bedroom PC which had a non booting installation that needed to be fixed it would only be out of actual necessity I would replace the installation on this computer, since everything runs just fine on it at present. The impetus for MainPC was Qgis compatibility for the most part after perhaps a rash decision to run a beta version of Xubuntu for a time.