We've used them sporadically as well. No problems to report. We offer up the cert at the time we order, in case the staff needs to verify anything. Service has always been the same as w/o using a certificate. They're good for us, because we don't have to start the "where are we going for dinner" discussion that invariably ends up with one or both of us cranky and having cereal. This way, we pull out the file for certificates and look to see what holds appeal to us that day. Good luck!