After two nights on this (one Jade, Amethyst, Cobalt and one Jasper, Amethyst, Cobalt) we still haven't managed better than 50% or so. Our main problem remains that the tanks haven't got it figured out yet, but we're finally starting to get some wipes that are everyone else's fault instead - jasper chains are a common problem, as is DPS standing in mines, and healers running OOM because there's too much incoming damage and not enough outgoing damage
We'll get there sooner or later - in the meantime I'm simultaneously glad that this isn't faceroll (shudder at the memory or Morchok) and worried how we'll fare on subsequent bosses if people are saying this one's the gentle introduction.