I don't install any IM apps - just BBM. I rely on SMS, BBM, or good old email.
I have used BeeJive, and thought it was going in the right direction, but it seemed to consistently hammer my battery. I haven't tried Trillian on my BB. Used to use it exclusively on my PC, but I guess I've just migrated away from IMs altogether. Not sure if that's a helpful opinion, but there it is.