It's a good question - how many active accounts? I don't know where to find stats on that yet, but I'm interested as well.
Yeah, same posting key from Hive... which is same from Steem for many of us. Unless you started more recently, or changed your keys at some point. It's definitely worth logging in and looking around, anyway. You may find, like me, that it offers something Hive doesn't, while still having a similar function and feel. A lot of good people are ending up there.