> "And, more importantly, RCV is a stepping stone to multi-member district STV proportional voting"
I agree that proportional representation is a huge deal, but I suspect we can do better than STV by changing what the election results mean. Currently in every system I know of we treat it as a binary choice; a candidate is either a member of the set of candidates who won, or they aren't.
A different way to do it is to allow every candidate who receives some minimum threshold level of support to be elected, but when voting on issues each elected person's influence is weighted by the level of support they received in the election.
This sort of system is compatible with FTPT, RCV, or approval-voting style ballots, but the differences matter less as long as you can say of the vast majority of voters (assuming an omniscient view -- privacy of votes would obscure the actual data) that that voter clearly has a representative in congress, and that voter delegated the same amount of influence to that representative as any other voter. (People who only voted for fringe candidates that don't meet the minimum threshold lose out, but that would probably be rare among people who actually pay attention to politics and aren't casting a protest vote.)
If this were enacted for the U.S. House of Representatives for example, the likely outcome would be that each state would have at least one Republican and at least one Democrat who would wield different amounts of power depending on how popular Republicans and Democrats are in that state. You'd also have Libertarians and Greens and Independents and whatever else. A state might have two representatives after one election and ten after another, and it wouldn't be a problem because influence is the same.