To whom...,
The problem with proportional representation is that it puts more power into the hands of the political party. While it may increse diversity in the short run, the very problem that American politics is overcome by at the moment is the excessive power of *party* money in politics. Proportional representation would only increase that power.
The real issue is access to the voters and the political party is actually the antique solution to that problem. The technology is available to create nationwide soapboxes and that is the real answer to diverse politics.
peace