Oh and don’t forget to take backups of your /home. Thats good practice for every desktop environment.

The config files of the major desktop environments have become a mess though. Plasma absolutely shits files all over ~/.config and /.local/share where they sit mingled together with the config files of all your other applications and most of it is thoroughly undocumented. I've been in the situation where I wanted to restore a previous state of my Plasma desktop from my backups or just start with a clean default desktop and there is just no straightforward way to do that, short of nuking all your configurations.

Doing a quick find query in my current home directory, there are 57 directories and 79 config files that have either plasma or kde in the name, and that doesn't even include all the /.config/* files belonging to plasma or kde components that don't have it in their name explicitly (e.g. dolphinrc, katerc, kwinrc, powerdevilrc, bluedevilglobalrc , ...)

It was much simpler in the old days when you just had something like a ~/.fvwmrc file that was easy to backup and restore, even early kde used to store everything together in a ~/.kde directory.