Can anyone explain the difference between using a 100K or a 200K pot in a wah pedal? Is the treble to bass sweep wider on one? Is it a difference in actual sound, or just feel? I just don't get the difference it would make... I'm a bit confused.

The 100K ICAR I tried just sounded too abrupt to me.

Anyone try out the "BlackTop" 200K from Smallbear? Is it a good quality pot?

200k will probably give you a really wierd sweep. The closest thing I have done to this is replace the 1k bass/gain resistor in my wah with a 5k pot (should've been a 3k). It sounded so cool, but was probably unusable as an effect. It was super-bassy with a kinda of a 'thwah' effect and rocking the pedal rapidly made a warbling sound.
200K wont give you a wider sweep. The design of the enclosure and the ICAR taper gives you ~75K of sweep.

200K will just let you play with 75K resistance above 100K.