I think most merchants would be reluctant to hand over any goods/services until the payment is confirmed, no matter how small the risk of double spend etc is. It's a psychological thing if nothing else.
mh, thats not the case if the risk is not on them.
in paypal, they hand over the goods, regardless that there is a chance that paypal will never see the money,
because thats paypals problem.
and paypals doesnt care because the risk combined is so low, and already priced in.
so if a plattform uses drk´s and takes a (little) fee to organise the transactions, taxes, servers, and combines the risk,
.... here you go.
but, i agree: if duff found a way,
this will be huge, because you dont need a platform to even out the risk.
wordpress-merchant-drk-plugin, i see you coming.