I like this suggestion. It would make things both easier and faster. I don't see any major compatibility issues either, except for things like this:
on *:text:*:#[color:red]:[/color]msg # you said[color:red]:[/color] $1-
The new mirc would probably interpret
msg # you said as the CIDS field. Only a very intelligent parser would be able to guess the scripter's intention, and not always.