In reply to jhw:
I wouldn't advise it unless you're well practiced in long welsh climbs in the cold and wet, and would definitely not advise climbing it in the snow!
I've got up to the knights move without much fuss in the wet in boots, but once I was there I took a stupid sliding fall - this was my fault due to trying to rush as it was getting darker and wetter, but its not easy in boots up there, and I can't imagine rock shoes being amazing on some bits in the wet.
As mentioned before if you take the wrong route up high, to the right of knights move, you end up on the super direct or the direct route and if you go left on knights move then thats just the wrong route. All are harder - (VS, S etc) and I know people have been rescued from some of them!
Like I said before though if you're used to this sort of situation then you shouldn't have too many problems, though I'd still say snow = bad on GA.