Mine has arrived. Surprisingly clean, nothing worse than a bit of dust inside it.
MX blacks are unbearably stiff, I swapped the stems into my main keyboard and I'm now typing on MX reds, which feel pretty good. Haven't had any problems with accidental keypresses yet, but then again I haven't used it much yet. Nice and quiet too.
As has been previously mentioned, the black keycaps are much thicker than the beige/white ones which shipped with my g80-3000 (also made in the Czech Republic), and they also weigh significantly more, both are PBT. They produce a lower pitched sound than the beige caps, and I'd imagine that the beige caps would transmit more of a tactile bump than the black ones, though I haven't confirmed this as I can't be bothered to swap any more switches today. Doesn't apply to linear switches though, of course.