Ranked voting is superior, full stop. It would be especially useful in the US where if you don't vote blue or red you throw your vote away. With this if you vote an alternative, if they somehow win, good. If not, you still get your say in the blue or red choice and the US gets to see a true picture of what people want. New parties could spring up safe in the knowledge that it isn't doomed from the start by tactical voting as it is now, leaving these two bloated monsters without competition.