As usual, you are always a step ahead .
And your conclusion is always true:
"One thing we can say for certain with a system that is as rich as the Moodle quiz, which so many teachers are interested in pushing to its limits, is that no matter how good we make it, there will always be more ideas about how to make it even better. Looks like I won't ever be out of a job --Tim Hunt 13:37, 11 October 2009 (UTC) "
Pierre