Yeah, I think there are a couple things to consider with voting.
First of all this would theoretically be a community of serious RAW enthusiasts, so they'd know what they're looking for. Seeing blown highlights, clipped shadows, etc. would theoretically make them rate something down, even if the overall contrast and tone were "pleasing".
I think it would also be good to have at least a few categories for rating, perhaps with the final score an aggregate or something. So for example rate on the following attributes that are particular to RAW conversion: Range Preservation, Detail, Overall Appeal. Careful selection of the rating criteria should help ensure reasonably reliable results.
Methods to discourage favoritism might be necessary as well. It would be important to consider whether votes should be anonymous. Votes might also include comments (optionally). It could be like ratings/reviews on e.g. Newegg or Amazon for example (Newegg perhaps more applicable as the review there are generally short).
The idea of the site continues to evolve in my mind, but the core concept is definitely consistent, and remains appealing to me. I still don't hear a lot of interest from others, though I certainly appreciate the feedback, ideas, and constructive criticism. But, would you use the site?

- Oshyan