Honestly IRV is _even worse than plurality_. It doesn't solve the problems it sets out to solve (it entrenches two-party domination [1]), it has ridiculous monotonicity violations [2], all for a lot more complication in counting the votes (you can't distribute the counting well without transmitting the contents of all of the ballots) and possibly wrecking the secret ballot (you can encode and buy specific down-ballot rankings).

Seriously, it's all of the disadvantages and very limited upside.

[1] https://rangevoting.org/TarrIrvSumm.html [2] http://zesty.ca/voting/sim/