Yeah. Unlike most commands, you can't use a "." to hide what is happening in MSG. I'm not really sure why you can't use .msg the way you can use .notice or similar. Actually, I seem to remember it being possible prior to 6.16, but I could be remembering it incorrectly.
You CAN use a "." to hide what is happening. It hides it completely from you. Open another mirc and you will see the channel message, but you will not see it with the mirc that's originating the message.
I refuse to engage in a battle of wits with an unarmed person.
Strange... I've had issues with .msg in mIRC 6.16. It gives an error message. I'll have to test it out later. Maybe there was some other issue... though it worked just fine when I had removed the ".", so we'll see.