How damaging is a collection charge off?

Short Answer. Very damaging.

I don't know the exact numbers for a charge-off but I do know that FICO recently revealed how their damage points work on some other items.

For example, if you have 680 credit score and have a 30 day late payment, your score will drop 60 - 80 points. If your score if 780, it will drop 90 - 110 points.

That's quite a bit. And I know that charge offs are viewed much worse.