Yes! Thank you! Let me add some notes though.

In my observation, splitting the mentor matching and project matching sessions was very successful. We had two rooms that were close together for both sessions. I was able to help people create posters in one room while we paraded introductory material, mentors, and projects in front of the newcomers. I heard lots of positive feedback, but then again, that might be because I was an organizer. I'd be interested to learn what the post-hackathon surveys say.

One other note I should make is about the opening session. Rather than doing an open mic session, we instead limited the open mic to "newcomer friendly projects". That went less well. I'd only set up the official definition of a qualifying project a week before the hackathon and no one read the email. So it was a surprise when people were finally in the room. Despite this hurdle, I think that the exact same strategy will be more effective next time because people will be expecting it. So I recommend a re-try.