I just found something of minor concern. I had a long line in my clipboard and pasted it by accident. Well with mirc 7 it split that line into 4 separate lines when it sent it to the chan.
So it'd be nice if there was an option like the current warning for pasting multiple lines. Because I just made a long line and it split to 8 messages, which I could see as a problem.
I think having it check how many lines a single pasted line would be split to and if it's over the "Confirm when pasting X or more lines of text" option warn the user.