I guess it depends on whether you're at the front of the train or in the middle - there also seems to be fewer people at the platform 1/2 exits so there isn't the same crush to get through as there is on the main concourse. I reckon it's quicker to use the stairs but then I tend to take the steps 2 at a time - I don't often go that way - only when I'm on my way to a morning gym session (which,oin these dark winter mornings is a very rare occurrence)