Theuns,
Well, it sort of depends. The info I've heard "second-hand" (and don't ask where I read this as my memory is shot) is that there is a slight step when you press the slat in on the ground. This is because the leading slat has a tendency to pop out in slow or no speed. At speed, however, the slat was pressed in by air flow and it was pretty flat.
That's the story anyway. May be BS, may be not.
At least you can claim you heard it from a "reliable source".
Gary