I actually like StackOverflow model: If you downvote someone, both of you loose a karma! This helps make people judicious decision on when to use downvote, at l

I actually like StackOverflow model: If you downvote someone, both of you loose a karma! This helps make people judicious decision on when to use downvote, at least avoids it becoming "disagree" button. This is super important because otherwise people become afraid of expressing unpopular thoughts and the forums become echo chambers. Disagreements should be expressed by writing comments, not pressing buttons.