Eh, I'm not planning on cancelling unless a bunch of my LR responses were different from the consensus. I honestly don't know if I would ever improve with further preparation, as I've been studying on and off for a year without any real gains. It's just that I always miss a couple per section, usually. I don't know if I'd really do better enough on future tests to all-out prepare and such.
Honestly, what it came down to in determining whether or not to postpone/cancel was the amount of sleep I got, how rested I felt, and then how I felt about the test afterwards. Yeah, I think I probably would've scored a couple points higher had I prepared more, but at this point, I don't feel it's worth it. A bird in the hand is worth three in the bush and all that.
Everyone seems to agree it was an extremely difficult passage, and I'm hoping the scale will reflect that.