RSVP's

So I need everyone's opinions on RSVPs. We are trying to decide if they are worth it. With inviting 750 people we are trying to figure out if we would actually need them. Even our caterer said that because we are having a buffet style meal that she usually doesn't even go by RSVP's she goes on a percentage of the people invited and that is how many she cooks for regardless of the RSVP's the bride gives her. She said that too many people say they are coming and don't actually come and too many people just don't send them back. We are going to be sending out around 325 invitations with stamps we could save around $150 plus the hassel of sending them out and making sure they are returned.

Does it look tacky to not have RSVP cards because I don't want that but if the caterer is going to go by a percentage anyways is there another use for them. Opinions please?!?

We were actually thinking of doing cards like these instead since they come with the invitation kits and this card is actually what our invitation kits look like. Do you like?!