I think the value is what needs to be refunded.  That is about 40BTC right now.  That way, no one is really at a loss.  Of course, my reasoning falls apart when you consider that if the price of gold doubled then it would be ok to send only half an ounce; if you consider things as only the value they represent.  But, Gold is a commodity and Bitcoin is a currency.  Bitcoins represent buying power, and so if 40 BTC were refunded then the gold coin could just be bought elsewhere.  This way no one could hedge anyone (as far as the currencies are concerned).