About the Cherry 4100, lets just say this - I put my Model M away. I love it, it has these little black mechanical switches that are short throw and tight, with a satisfying snap as the key strokes register. I can type as fast on it as the Model M, plus I don't get any hand fatigue. The sound is cool to, but not too loud. I love the size, which is why I am considering the Happy Hacking Keyboard.
I think I'm going to buy one with my financial aid money (as a non-trad, I get a decent amount). The cost doesn't scare me if the product is worth it.