I've never used Identica and never would have. I was (and still am) a very heavy Twitter user and have lately taken up Google+ because that's where all the open source geeks are. Rolling out my own StatusNet wouldn't really have been that useful either.
Pump.io, though, is something I'm keeping a very close eye on. I've been considering rolling out my own server ever since I heard about it. Two reasons: 1. federation, 2. Apache licensing. I'm actually surprised this article somewhat lately discusses the 2nd aspect. I think that this is a strategically well thought out move that will show its value in due time.
Though I don't have the resources to keep updating a server to follow development versions, the more mature pump.io gets the more likely I'll roll out an instance.