The net effect is an advantage to the candidate you would NOT be voting for.  For example, George Wallace in 1968 with 13.5% and Ross Perot in 1992 with 19% of the Presidential vote, pulled votes from the major candidate who was most "like" them and would have likely received the votes they received instead.  Preferential balloting overcomes this issue and gives a significant boost to those long-shot, third party/independent candidates.  I think it would help to address the stanglehold the two major parties now have on American politics.  regards, Gary Crum