Had a brief foray into keeping local crayfish as a kid, small, unheated tank. That's the extent of any personal experience...
But with no comments yet, I've never heard of keeping them together. Can't imagine it's a good idea. My understanding is discus temperatures would stress them, but that wouldn't be my main concern. They're also predatory, with slow fish and lower level fish being they're easiest victims. On the other hand, they're vulnerable to larger, aggressive cichlids-- I've seen stories. I've only really seen them work with quick, mid and upper level fish that aren't too large, some barbs, hatchetfish... Even then, be prepared for the occasional one to go missing from what I understand. I also remember being on a forum where someone said they took chunks out of their fish at night.