I agree with Crescent. Any ratings system is fundamentally insulting. Quantifying one's work is useful for contests or sporting events, but not art. Even sports that have an artistic component, like figure skating, have a built in fail-safe for extreme "high-low" scores: either are automatically eliminated. It's true that members might rate according to personal political, religious or sexual tastes and ignore the artistic merit of a piece. They do it all the time. There's nothing more valuable to an artist who requests feedback that the good-old-fashioned written word.