Well, you can easily join multiple networks and channels using a very small script (for those willing to do so), and the reload logs option would let you join the channels and still see the conversations. The only thing you'd lose would be query windows, though I'm sure it would be a simple matter to script a "suspend" option that saves all open windows and then rejoins them (including queries) and then reloads the logs.
In any case, it's not a bad idea, even if it wouldn't be much work to script. I wouldn't mind seeing such an option.
