I agree about the point regarding tile based window managers. Few others come close to maximizing productivity of windowed apps; but OSX's various other productivity enhancing features make it not worthwhile to switch back.
Of course tools (hardware and software) can only take you so far. I find that most productivity comes from being surrounded by sharp hard-working people trying to push the envelope. Working with hard-working people creates a cyclic motivational cycle, all pushing each other to be more productive.
I think you can get XMonad working on OS x; I know a couple of people who were using it. I also think the "productivity enhancing features" broadly overrated and better in Linux, but that's neither here nor there.
Of course tools (hardware and software) can only take you so far. I find that most productivity comes from being surrounded by sharp hard-working people trying to push the envelope. Working with hard-working people creates a cyclic motivational cycle, all pushing each other to be more productive.