I just A/B'd a chorus before and after my TK-421-X. With the chorus after, the wobble of the chorus was really dirty, to be expected. It sounded good though. With the chorus before the TK the dirty chorus wobble had cleaned up a bit and the note definition was much better. I actually prefered the chorus in front of the fuzz, but as always, I'm sure both ways have their uses. Doing it that way was definitely worth trying though.
I did try two choruses, before AND after the TK at the same time. That was interesting, a lot of wobble but a huge sound.