The data would be pretty confusing, without analysis. I'm also assuming people with enough of a life that they wouldn't try.
Instead of (or in addition to) raw upvote/downvote data, you get a "compatibility score", where 100 means you're soul mates, and -100 means you're mortal enemies!
Instead of (or in addition to) raw upvote/downvote data, you get a "compatibility score", where 100 means you're soul mates, and -100 means you're mortal enemies!