Interesting idea. I could see potential problems, though, if someone gives negative feedback for another member and that member complains to staff about it (or arguments of the "he said, she said" type ensue). Only allowing positive feedback would be a way around that, but it would lessen the usefulness, although it might happen anyway as I've noticed a tendency in this community to be very forthcoming with praise about vendors and luthiers, but strong reluctance to offer critical or negative feedback about them (which is usually only exchanged privately). Probably partly out of politeness, and partly out of fear of attacks from fans of the vendor or luthier (not an unreasonable concern, as some threads over the years have shown where posters became the bad guys for daring to even mildly criticize popular dealers or makers).