The newer Model S introduced the 'fn' key left of the left super-button, resizing that one in the process. Now the old key-caps don't fit on the newer model any more. It also doesn't feel quite as solid as the previous Model S.
The newer 'cloud connected' keyboards take DasKeyboard in a direction that makes no sense to me. Fortunately, there are now plenty of competing mechanical keyboards, for much friendlier prices. I got a nice mechanical keyboard for €90 on Amazon last year for my girlfriend (Fnatic Gear Rush Silent LED); no complaints whatsoever, and her colleagues are jealous of it.
My next keyboard won't be a DasKeyboard.