In reply to Jamie B: I did an early ascent of West Buttress, well before it was in any guidebook & for a while thought we'd gone of route as the there was a short section which seemed very hard for III. But when it appeared in a guide it seemed we had climbed at least the first half of the route but think we went somewhere else higher up.
I was also on the FA of Stairway (same winter I think ) which was pretty much the easiest way up the buttress on day of poor weather - I remember most beng very easy - could well be II