You're right, Robin, with your comments on the origins of the preferential system; I was trying to be succinct but descriptive enough for nonaussies to cope with it and the basis for "why go to the trouble'. Except for the fact that there's a swag too many methods of casting votes ("correctly", even) in the US already, as well as the fact that the plethora of positions voted on at any election there, I'd almost be brave enough to recommend, politely, they took a good look at it as a way of dealing with the stranglehold the two (funded) parties exercise.

Cheers, Rowan