I can add from my daily use experience.

4 IM accounts are always active when I'm on wi-fi and this way with average usage of device battery last around 24h... good enough for me.
However when I'm out and on 3GP traveling around (usually underground)
I've noticed All of IM accounts keep trying to reconnect and eating battery very fast. If I'm at work in place where is poor network coverage this is happening every 10 sec and obviously trigger screen to light up. In that case battery last no longer than 6h for me.

So... just to test it. I turned all of IM accounts off.

Now on Wi-Fi or 3GP (doesn't matter really) battery last nearly 2 days.
I learned to turn them on only when I need it and there is good network condition for that. It's enough to have only one network error on the list and same issue happens.

Also I can't update the plug-ins for Conversation with PR 1.2. Each time when I re-flashed device and run the same backup ability to do that seems to be random for me. I can't find consistency here. I was trying to turn off/on repositories... no luck.