Wait, wasn't the deal that sellers could no longer leave feedback? When does that kick in, because a seller left feedback for me a week ago! Anyway, I think the whole idea of one-sided feedback is utterly ridiculous. Instead of sellers hurting buyers, sellers will no longer have a clue about whether or not someone takes too long to pay, if someone who tries to run payment scams, or other issues.
The best answer is so simple, I feel like I should be running the company! The only thing that decides whether or not the seller is satisfied is whether or not they get their money, right? And apparently the problem is sellers who hold off on leaving feedback in case the buyer gives them negative feedback so they can retaliate. Well then, all you have to do is set an expiration on when the seller can leave feedback. Obviously they'll get paid well before the buyer gets the product, so if they don't leave feedback by the time the buyer leaves feedback on the item auctioned, the seller loses the ability to leave feedback. It's simple and still allows people to know if a buyer has a good or bad rep.