I'm also looking for a replacement for the Microsoft Natural Ergonomic Keyboard 4000. It seems Microsoft stopped making them some time ago. I bought two more as

I'm also looking for a replacement for the Microsoft Natural Ergonomic Keyboard 4000. It seems Microsoft stopped making them some time ago. I bought two more as a reserve but they are already in use now. My ideal keyboard would be this keyboard but with good mechanical switches. I've tried a Keyboardio Atreus but it was too much of a change.