Comments on HN. Sorry! But I read it on the Internet, so it must be true.
FWIW I've seen the same thing said by other people elsewhere, though of course it's possible that they and the HN comments derive from a common source. Also, my understanding is that the amplituhedron approach produces the exact same numbers as enumerating Feynman diagrams does, just quicker and in something more like a closed form, so it has to be as local and unitary as any other way of doing QFT.
I recently ran across a rather interesting result while browsing the Internet:
Physics Discover Geometry Underlying Particle Physics
Unfortunately, I'm still at the point in my education where my best response to new physics is "cache for later," and the fact that it claims to eliminate locality/unitarity seems decidedly odd to my mostly-untrained mind. I notice I am confused, and that LessWrong has a rather large number of trained physicists.