I've used restaurant.com in the past, albeit infrequently, but only on places where the minimum spend is something we could easily envision for a single meal and where they don't have the gall to add on an 18% tip for using the certificate.

At any rate, changing the minimum required purchase from $35 to $150 is rather steep, IMO, and would have me starting the charge dispute process with my CC issuer, as I wouldn't necessarily want to carry the credit at restaurant.com.