Couldn't you just set the seats in a kind of locked state as soon as the transaction arrives ( 0 confirmations) and transfer the seats as soon as it's confirmed?

If the transaction get double spend before it gets cancelled. I understand why there is a time limit to send the coins, but why is there some for them to confirm?

Also time to say, I really like the nasty fans solution, beats really beats any exchange IMO. Thanks nonnakip