Literally, the first thing that came to my mind when I read the title of this thread was:
Seriously, I highly doubt anyone can not tell that a body that can handle high Iso that perfect, and a 85mm 1.2 lens are probably the best base for shots in such circumstances.
my 6D + 50 1.8 can do great street photography at night too and many folds cheaper than your 1dx + 85 1.2.
talking about IQ/price ratio, my combo is greater than yours.
You compare a 50 1.8 to a 85 1.2? Heck, even a 6D to a 1DX? That is almost more trolling than the original post here.
1DX, 5D Mark III, 5D Mark II, 24-70mm 2.8L, 24-105mm 70-200mm 2.8 Non IS, 100-400mm 50mm 1.4, 85mm 1.8, 85mm 1.2L 135mm 2L, 580EX II, 600EX-RT