I like this idea too. I'm not a songwriter or much of a musician but i know a good mix and a good tune when I hear it. I'd love to know why I like one song more than another, why it works etc. I think this would help in making production decisions on mixes, muting parts or re-arranging sections. Again because I don't think of myself as a producer, I'm an engineer and love the gear and the tech side plus I've always worked with musicians or producers that told me which direction they wanted a song to go in and I just facilitated that.