I tried to squeeze it in this afternoon, between a couple of other critical tasks for flying home early tomorrow morning, but ran out of time. So I only got as far along the Roc Cornafion S ridge to where the horizontal traversing ends and the sustained uphill climbing begins. For sure the Roc looks rather dramatic approaching from the South - (and the overall setting is pretty and pleasant, and included views of some key high peaks of the French Alps).
Key thing I found was that the (short) abseil/rappel at around (N45.0565 E5.5988) is easily avoided by going back S along the ridge 40 meters to a small notch (N45.05603 E5.5986), next off the ridge crest down East about 20 meters, then traverse N across the head of a gully, and then diagonal up to rejoin the ridge crest at the bottom of the abseil, and continue N from there.
I thought the moves after the abseil were more interesting (and less vegetated) than the earlier section south of the abseil point.
I started hiking from the west side from Parking on asphalt, GPS lat long approx (N45.0730 E5.5793) about 2 km E up from the village of Villard de Lans. The trail up to Col Vert (N45.0528 E5.5972) was straightforward, but unfortunately rather muddy due to logging operations.
I sort of doubt it makes sense to try to link the Cornafion S ridge with the Aretes du Gerbier ridge traverse, since the preferred directions of the two routes are opposite.
Ken
Post edited at 20:30