That was as of Jan 8. The hacking email went out on Jan 7. As of today, Jan 13, the board has 156,107 members of whom 7,071 are active. So we gained 124 members (wow) and 245 active members since day 2 of the crisis/catastrophe/brouhaha. Netting out the new members it seems that 121 old members have dropped by, including manhattan. That’s less than 1/10th of one percent of the membership. Admittedly, I didn’t get a snapshot from before the announcement. (IIRC, it was something like 5800 - so maybe 1000 showed up early on? That seems high.)
At any rate, all discussion here of the Great Hack of 2014 involves those whom are highly unrepresentative of the underlying stolen database.