In reply to Pete Houghton:
Thanks all for the continued advice, with one of us weighing a 60 in one hand and a 30 in the other, and the second of us holding three nuts in one hand and the extra bits of metal we'd have to bring for the south ridge in the other, we wimped out and decided to do the south face instead. Setting off at midnight, it took just over fifteen hours from Montenvers car park to the summit of the Moine and back down to the car park. My map-and-string technique doesn't quite tally with my friend's GPS watch claim of 42km, but it certainly felt as though we'd covered that kind of distance. Of course fifteen hours isn't that good a finishing time for a marathon, but very few marathons have the Aiguille du Moine as their halfway point.
We are most glad that we didn't try for the original original plan of the Whymper on the Verte, as from the summit of the Moine it looked like the lower half of the couloir was getting horrifically dry, and indeed when we passed back over the terrace of the Couvercle hut later in the morning, we met two teams of two who had both bailed on it after complaining of a lack of snow.
Smashing day out anyway, and my last trip up into the hills for a while now, as I'm having ACL surgery in five days.