Click to enlarge. SO close
So, what do you see? Beside the color shifts between the projectors, look at the wall stones on the near right, also the darker parts of the frescos painted on the stone under the lights on the right, and in the fireplace. And the lower stones in the arch.... Actually what you are probably seeing, are three enlarged images, that all have very similar shadow detail capabilities. Overall, the BenQ W10000 (on this image, has the advantage, with a slightly higher contrast look that makes details stand out more. As to the Panasonic, this is the type of frame, that does allow the dynamic iris and lamp, to do their thing, and as such, the Panasonic rises up and performs extremely well, in shadow detail.
This image below, from the beginning of Phantom, is in black and white and is extremely dark in the movie. The HD81 handled it extremely well.