So, apparently, the CMC-6s I have do have removable caps. Of course, I then headed over to soundprofessionals to see if they have any slimline card caps, and they don't. They have omnis in stock and that's it. A cached google search tells me that they once stocked them, but don't anymore.
Would anyone else sell these? They seem like normal AT slimline caps...
I'm taping Iron & Wine tonight with my omnis, but I hope this'll be one of the last shows I have to do with them.