I cancelled in September. My LSAC LSAT page shows that I earned a score of "Candidate Cancel".
I expect that is what the law schools will see, as well. And I have also heard that most schools don't care very much about one cancellation. (But most schools take the higher score now. Check the policies of your target schools.)
My advice: LSAC gives you get six days to make this decision. Take them. Sleep on it for at least two nights. Make sure you will have no regrets one way or another. Especially now that this test is over, I'm really happy I cancelled last time. Even if the curve is brutal, I know I did my best on this test, unlike September. But if you are a person who will always wonder how you did, you shouldn't cancel.