Yes, the K400 also works perfectly with non-Microsoft OS. I have used it with Mac OS, Linux, BSD, etc. With Mac OS, just remember that the keyboard shortcuts are a bit different, e.g. "@" is Mac-typical AltGr+G and not AltGr+2 if you do not set OS X accordingly. Works perfectly even on newer Linux distributions, no restrictions in functionality.

I have this on a MacBook Pro and it works fine.