Stash,
Guild Chats (the forums) take up more room on the server then IM will. Buying bandwidth is more costly then find a middle way and shut down something to create a new, less spacious solution.
I don't think the IM is a bad idea, just my luck that hardly anyone is on when I am (timezones suck
). Also, a Guild Chat (integrated in IM) is faster, when you catch people online and as said before, takes up less room.
Ever thought about that my dear friend?