I'll jump into this one.
The lower house in Australia uses preferential voting. I think the important thing to remember about preferential voting, from my perspective, is that, sure, it feels better to the voter when you cast your vote, because you don't have to vote strategically. But that is the only problem that preferential voting solves compared with first past the post with just a single X. You don't have to vote strategically. You can list the parties in your order of preference, and it's an accurate representation of a voter's wishes.
In the Australian experience, it does consistently lead to people who can go their whole lives with their first-preference vote never counting. It creates voter inequality between different voters. Some voters have their first-preference vote count and some voters only have their second- or third- or fourth-preference vote actually count.
I think the inequality it creates between voters is unfair. It's still a winner-take-all system. There are winners and losers. It turns some voters into winners, “Oh, great, my candidate got elected.” Some voters, however, just have to suck it up, “Hey, the person I wanted didn't get elected.” With proportional representation, everybody's first-preference vote counts equally.
I think preferential voting should be off the card. The five values of this committee point very strongly toward proportional representation. Let's make this discussion about which model of proportional representation you're looking at.