Binary is good. Do I rate your comment above a 6 or a 7? What does 7 mean to the next guy, and is it the same as it means to me? Up down is good because I only vote when I feel strongly about it.
1.My own perspective is that it does not matter whether it is a 6 or a 7 and who interprets it how. That is the whole point of a subjective system it is not objective.
2. I believe subjective systems should not use numbers or other notations and therefore I suggest a slider not 10 radio buttons or a rating system.
3. I do not imply that the binary/objective system is no good. It is good for some applications, I would just prefer a more subjective measure around things which incorporate human opinion.
:)