Hebog's OK if you get the lines right, especially early on and even after Hebog there's a few lines, actually back on yourself that can save time off the summits. Gyrn can cause trouble too, I just stuck to the LHS of the wall until quite high up.

I was reading a thread today that reckoned for a sub 24 hr BGR you run for approximately 6 hrs.

Have you considered poles? These seem to be increasingly used. Steve Birkinshaw was talking about using them on his lakes 24 record.