About which version are you talking? It worked perfectly in previous versions, but checked just now in 7.0.1 and you are right. Have to check in CP8. Bummer, what has changed there?
Moreover, when I capture the answer with the Success/Failure actions, the user variable is populated, but it is cleared together with cpQuizInfoAnswerChoice.
Another blog post that I have to take off line. Time to stop totally with blogging, I'm afraid.