Granted, your first scenario is extreme.

What I question is what responsibility would I have in giving a purchaser a refund prior to getting my merchandise returned, club member or not?

There are of course differences between buyer and seller at times. It is my assumption though that feedback is based upon the TRANSACTION. Was my payment sent out in a timely fashion? Did I receive my merchandise in a timely manner? PERIOD

If buyer and seller each played the waiting game to see who would post feedback first.... there would be NO feedback at all.

The purpose of feedback is to give some insight as to the character and reputation of the other party. You have the ability to refuse bids or for that matter to abstain from bidding on any auction you are uncomfortable with.