Here’s the main consideration from my point of view as an organizer:
Lesswrong.com is still the #1 source of newcomers to the San Francisco meetup.
We haven’t had much chance to try out the new meetup functionality on lesserwrong.com yet, but we really need it to work. This is our community’s primary source of new blood, and it is super important for that to be all set before the migration happens.
Yes, I’ve had many of our newcomers tell me that they showed up because of that feature (not because they went looking for in-person meetups). Discoverability matters.