Don't expect that to be a solution though. As you know, CCL schedules all its meetings through Meetup, which has an RSVP system baked in. What we see is that most people (especially the regulars!) just don't bother to click the RSVP button. Which sometimes leads new folks to think that meetings will have a very low turnout, so they don't bother coming. We've also had instances where the meetup organizer changed the schedule last-minute, and only emailed the people who did RSVP.

So unless you really hound people to use the RSVP system, RSVPs are typically inaccurate and misleading. 

They may or may not still be a net positive overall. But having an RSVP system would definitely not have solved the issue with a new prospective member showing up, pie in hand, to an empty sudo room...

Patrik