Mac specific keys isn't really required so much as it'd be nice. The features I use it for are for screen brightness, volume and track control. The tracks I can control via shortcuts. The volume is usually outright bypassed by my DAC but the brightness part I'm not sure if I can bind to a key press. That would be something I'd miss, though I can't say how much.
I'll definitely look at the brands you mentioned.
Right now the Das Keyboard is in the lead, assuming there is a lead to be had but I will admit I was considering one of the Razer mechanical keyboards. So you'd recommend not going that direction?
i would avoid anything razer except for maybe mice...they dont have the best quality control, whereas my leopold feels like it would survive a atomic blast. its a tank to say the least. My roommate bough the razer with the blue switches and it definitely feels very cheap in comparison. though i am also not a fan of lights/lcds/macro buttons, i like very not flashy keyboards, but i also like very well engineered/built stuff, hence why i love the Leopold