No, I don't think preferential ballots would turn our system into something that more readily produces minority or coalition governments. The question might be, again, how the party system changes.
I think we'd see less drastic change. I don't want to say that nothing would fundamentally change, but under preferential balloting, we see that in extreme cases it sometimes ends up being even less proportional than first past the post. Even when it doesn't, the improvement in proportionality is relatively minor. I don't think we would see, even if we assume the party system doesn't change, dramatically different vote outcomes. I would call that more of a modest change than one to PR.
I think the virtue that you had put forward for preferential balloting, because so few people do, is that we would at least no longer be able to say that there are members being elected with 30% of the vote within their riding and they get a seat. I think that has some appeal for some people.