I assume you pay before they pour out the coffee, otherwise it could go cold while they are waiting for enough confirmations.
nice comment,watching for next coffee with cold mug 
Payments in the stores within a few seconds all the time, my friend. Doesn't depend on the blockconfirmations at time of payment.
The Guldencoin team has thought about that
If you want to join our forum:
http://guldencoinforum.com/index.php/topic,472.msg3560.html#new
or the ANN:
https://bitcointalk.org/index.php?topic=554412.msg8586498#msg8586498