I have left Beejive for eBuddy Pro and I'm very happy with it! eBuddy Pro is super fast on iOS4 with multitasking and lightweight. My only real issue with eBuddy Pro right now is that there is no copy & paste in the app, so if you want to keep a record of your conversation, DO NOT delete the chat or take a screenshot. eBuddy support let me know that they are working on copy & paste in a future release though. Buying the Pro version of eBuddy for me was a no brainer because of the 7 day login and no ads. The themes are a little to girly for my taste, but I like the classic default theme anyway.
Beejive definitely is a full featured app, but I didnt use half of them since I'm not a real heavy IM'r. For quite a few weeks now, I have been getting the random disconnects from Beejive using GTalk. Everything is nice and stable with eBuddy Pro. I'm not going to delete Beejive from my phone, it's an excellent app and might make it's way back to my dock, but for now, I'm using eBuddy. Pro.
Hope this helps!