I presented the paradox (the version where you know of 1000 previous attempts all confirming that the Predictor is never wrong), answered the questions, cut off some standard ways to weasel out, then asked for the answer and the justification, followed by a rather involved discussion of free will, outside vs inside view, then returned to the question. What I heard was "of course I would one-box". "But barely an hour ago you were firmly in the two-boxing camp!". Blank stare... "Must have been a different problem!"