I do use BB Messenger for my friends with a BB, which is most of my co workers. I do love that IM app and thats not changing.
My biggest question is if running all 4 apps is ok vs. getting one of those single apps? How big of a difference will be made, I believe I got a single user code for Jivetalk back when I had my Curve. Maybe ill try that when the Storm version is released.
Something to note is the IM+ application by Shape Services offers IM push. So with that application you can be logged into all the listing services mentioned without draining your batter or memory resources. This also eliminates the need for a constant direct connection