Just to add my two penn'orth, I'd definitely stick to the southern wall. Even in the dark it's a bit easier to follow - if you start going downhill to your right, you're going off course and need to concentrate! You'll reach a stile that has (or did have) a blue cup tied to it, then it's down and over a gully and onto the open bit where you'll be looking for the check point.
The old route used to go over that stile but it's out of bounds now, and obviously the checkpoint moved down from the trig to it's new location.
Good luck with it all of you, mebbe I'll have another crack next year!