I’m a fan of IRV too… and correspondingly a supporter of fairvote.org . IMHO changing the election system is the only way we will ever break the duopoly. Under the current system, if your candidate is polling anything less than 40%, he’s a spoiler. You are actually helping the candidate you DISLIKE the most, because your second choice isn’t getting your vote. This puts voters in a tough spot - do I vote with my beliefs, even though that helps the guy I HATE get into office? Or do I “hold my nose” and vote to make sure that the worst of the worst doesn’t get in?
3rd parties are only as useful as non-profit ideology advocacy groups. They have no chance of winning, but they CAN spread the message a little.