Hi SeonaVDP,
The reason for the change was to have the so called home row for navigation. W, E and R. Which is a very common navigation scheme outside of Blender. This allows you to work with the keyboard without the need to look down where your fingers are. That’s common to me 
Well, E was occupied now for rotate. So the extrude key needed another home. S was free now. That’s basically the story behind it
But nothing is lost. You can at any point simply switch to the Blender keymap. It is still available. We don’t have a reduced version of the Blender keymap though. You need to use the full keymap here. You can switch the keymap in the splash screen for example. Don’t forget to save the startup file to make the change permanent.
And finally – is there a definitive list somewhere of the new keymappings in BforArtists that I can print out and refer to when needed?
This list is a chapter in the manual. At least for the default keymap. The Bforartists full keymap needs still documentation, it isn’t included here yet. https://www.bforartists.de/data/manual/2.1%20Bforartists%20Standard%20Keymap.pdf