Forget the Samyang and Olympus etc. The 12mm Master Prime at T1.3 is the fastest by far.
I gotta say, that paint job is a real game changer! I can't tell you how many times I've lost my camera in the dark or wished it would show up more in car or window reflections while shooting. After all, if you're going to pay far too much for a limited edition camera with far too many pixels crammed into it, you gotta show it off every chance you get, right?