We do usually collect 50-100 new email addresses for our mailing list, and there are always several people who discover us for the first time at the Maker Faire and then start coming to some of our events. And yes, that's true even for CCL. I think the fact that the MF is in San Mateo really doesn't matter that much - visitors come from all over the Bay Area, including a very substantial number from the East Bay.
The number of kids at the San Mateo Maker Faire has definitely grown in recent years, but the main expo hall we've been in is still mainly aimed at adult makers, hackers, engineers, scientists, tinkerers, crafters etc. Last year we were adjacent to some scientists from the Monterey Bay Aquarium, the NoiseBridge booth, and the big Game of Drones arena; and I think the public we were getting was fairly well respresentative of those kinds of topics.
In the past we've also gotten some good press coverage from being at Maker Faire, maybe when DIYbio was still a bit more of a novelty.
Staffing a booth at MF is definitely not for everyone, but I do enjoy it. I also love wandering around the MF, and I always encounter tons of other people that do stuff that is relevant to me. Last year that included two other bioprinter efforts, some cool modular DIYable microfluidics, several bioreactors, and more.
Patrik