Even then, I believe it would be good practice to still have a bad traders forum. Basically a place where people can make claims/defend themselves. We want to build the community and having a forum of such would help the newcomers have a little faith in this system and being able to avoid rippers and the like.
There should be one sticky and the rest of the posts to open claims. However, there will be a need for someone to watch over and help mediate the problems as they arise.
Even if people have +X through the feedback system, you can simply click and find out what trades were real and which were cancelled. Either way, I vote that we should have a system/forum in place. It's just who wants to help mediate and run it is what else is important.
my 2cents.