I usually accompany DD (2) up and down the stairs, and she is pretty sure-footed, especially on the way up. Not so confident about her coming down, but I think that's partly cos I am always there in front of her, and I think that gives her a (false?) sense of added security, so she's not so careful.
Anyway, I'm just curious to know when I can let her tackle the stairs without my go-go-gadget arms in the immediate vicinity.