Firstly, I only read half the thread, because I'm in a bit of a hurry (so close to Xmas and all). Anyway, I don't really like the idea of the system you are proposing, and I have been at the bad end of a few transactions in my short Ebay career... I like to believe in people.
One time, I purchased an item for $1000 on Ebay, and when it was received it costed me an extra $800 to fix it (it was damaged, not as described).
I got on to the seller, and managed to get them to refund $250 after 2 months of negotiations... I was on the verge of going through Ebay fraud protection.
Anyway, I left negative feedback for them, because they screwed with me for 2 months saying it was my fault and such. And they retaliated with only 2 words (basically).
Me: Very bad experience with seller. Went $800 over budget.
Them: Don't appreciate neg. feedback. Money Refunded.
Money refunded-- ha! They make it seem as though they refunded the $800, when they only refunded $250.
So you see, the neg. feedback system works both ways.