In Austria and Netherlands who use PR, far right parties are leading in the polls.  Yes they are below 50% but don't rule out them finding a way to form a coalition, its anyone's guess what will happen after.  Ranked ballots not PR is the best way to keep extremist parties out.  The far right One Nation Party in Australia has no seats in the lower house where they use AV, but does in the upper house where they use STV.  It is because of run off elections that will likely (albeit no guaranteed) deny Marine Le Pen the French presidency whereas under PR should would likely get it.  We should either stick with FTFP or switch to ranked ballots, PR is a disaster we do not need.