or what you type goes where? /dev/null?

Same place it does when you typo a message to someone that doesn't exist... back in to a message to you (from root.)

By the time most people will want it, it is because they've made that error and it is already too late.

It's never too late for the next time.

I also suspect it would be cumbersome enough that very few would leave the setting on for long once they did turn it on.

I would use it and I suspect I'm not alone. I don't say much in the CB usually, but I do use /msg regularly.

Also, would it affect just the CB interface on the webpage, or all clients you may use? In the latter case, depending on the syntax chosen for it, would that require modifications to all the various other CB clients?

I suppose that it would depend somewhat on the implementation. As for existing clients, they would presumably need changes if they wanted to support the new feature, but they would continue to work normally without modification as long as you chose not to turn the feature on.

How much additional load would be generated

I honestly don't know, but I suspect it would be very little.

ailie reminded me of an old saying

Actually, I'm not suggesting this out of concern that I'll accidentally post something to the CB I'd be embarrassed about. I'm actually just irritated with the disconnect that it can cause in a conversation when, three messages too late, you realize that an earlier one went to the CB rather than to the person you are talking to. Or one of his did.

-sauoq
"My two cents aren't worth a dime.";