If you pasted 500 lines of text to a DCC chat window you will not get killed for flooding. You can paste as much as you like, because the information doesn't go through the server it does not disconnect you. Now, if you sent all that text through a query window, you would get 'Excess Flood'.
I suppose that is another risk ran with DCC chat, people can flood your chat window easily and, until you close the window, flood you. However, this is more of an annoyance than a risk.
Regards,
