Recently, I was flooded with a great deal of DCC chat and send requests, all bogus, and I noticed that they all take control of the window. Not only does the chat not allow you to kill them all, you have to continually hit enter/click "no" just to get rid of them.
With a few hundred of the bots doing this, I figured it might be a bit of a problem. I turned off all forms of DCC, but I don't think this is a viable solution. What I suggest is to not have a dialog open whenever a chat or send request occurs, but to just open a window that has a list of all DCC send/chat requests (or even the chats and sends themselves) and have an option to accept, cancel, resume, etc., sends and to accept or cancel the chats -- xchat-style.
It'd not only help when I'm flooded (though it just takes a lot of time, and the freezing of mIRC, to stop the flood (one still responds to PING requests)), but it'd be a bit easier to follow.