Just had a neg from a buyer who didn't receive their item because it was lost without out a trace using RM Recorded. I contacted HIM to ask if it had arrived a week after it was sent, because it wasn't tracking and he said it hadn't. I replied to hang on a few days and I would either give him a refund or send a replacement depending on what he wanted. You can guess the rest: not a peep more for two days then a Paypal Claim, which I granted a refund.
A month and a half later he leaves a neg - even though I was friendly throughout and gave him a refund straight away. I of course have left a neg in exchange, but it really pisses me off.
In the same situation, I most definitely would leave at most a neutral, probably a positive.
Teaches me for using Ebay I suppose.