The deal-breaker with all the Model M keyboards and clones is the scarcity of modifier keys.

I mean, you get only three on the left side, plus a giant spacebar that you will only ever tap with your right thumb in a single spot. That's good for Tim Cook, I guess, but any self-respecting computer geek will want to have more modifiers. My Ultimate Hacking Keyboard has a small spacebar on the right half, while the left has: Control, Fn, Alt/Option, Cmd/Super, Mod, and a special "Mouse" (emulation) key below the other keys, on the keyboard frame.

Some of the older keyboards are even worse in that they only have TWO modifiers on the left, which is a complete showstopper.