(Un)fortunately, I happen to be in Chamonix that weekend. What a pity
As others have said, the hardest part on the full trog is that part of it shared with the Half. If the clag is down then from Cock Hill to High Brown Knoll and the first part of the section from there to just after the air shafts can be tricky. Definitely worth recceing and getting your bearings sorted out.