IRV has the problem where gaining support can actually cost one the election (nonmonotonicity).  From <a href="http:&#x2F;&#x2F;zesty.ca&#x2F;voting&#x2F;sim" rel="nofollow">http:&#x2F;&#x2F;zesty.ca&#x2F;voting&#x2F;sim</a> it seems that approval voting would work reasonably well.