I don't understand this fixation with confirmations in an IRL payment situation. You need to wait, at most 10 seconds to listen for a race attack, and only 2-3 if you have a well connected client. Who in their right mind would spend millions of dollars on making a 51% attack and then use it to get out of paying for dinner? Its much easier, cheaper, and simpler to just dine and dash then it its to create a race attack, must less a 51% attack. Confirmations are only needed for transactions large enough to warrant a 51% attack. Otherwise you can accept an unconfirmed transaction as a-ok if you have a well connected client designed to listen and warn of a race attack.