I remember the early ones specifically being Model M's, but because of the drastic change in case, the sound qualities change a bit. The early ones also killed typewriters, but I highly doubt that he does that anymore. He has to make many of the keys custom, anyway (I'm pretty sure typewriters don't have a numpad, a windows key, or function keys!), so I think he makes ALL the keys (or has someone else manufacture them for him) to keep them consistent and to keep the cost down.
Looking at the side views of some of the keyboards, he appears to use Cherry switches for his recent models (most likely blue or green, but I don't see why he doesn't give people the option of clicky or not. Maybe he wants all of his board consistent).
On the topic of style, I enjoy most of the boards' styles. I do find myself liking the simpler ones better (the art deco ones have clean lines and a defined theme). The steampunk ones tend towards a tarnished look that I wouldn't like on a keyboard and seem to use colors that emphasize how out of place they are (even with a fully themed room, some parts are clean, while others have the steampunk brass that don't go as well with each other as say, silver and black). And then there is the industrial one... it just stands out with it's fake scratches...
[Edit: I was wrong about the Cherry switches. He appears to use black ALPS. This video briefly shows him making a keyboard:
(Yay! He's not killing a typewriter!)]
