I think we benefited from a certain amount of luck on that horizontal section near the top.
At the critical point my Land Cruiser's rear end started to rotate anticlockwise and slide away down the slope. If I hadn't stepped carefully on the gas, had a locked center differential and also a fairly new set of Duratracs, Oscar and would have gone backwards over the edge. Given that by the time I hit the gas we were at an angle to the trail's direction, if I had overcooked that maneuver we would have bounced off the left side of the track (sharply angled, as you can see in Dumpolina's photo above), and gone forward over the edge to our right.
Consider also that the young man directly in front of me, in the red Jeep, went across that stretch with open differentials and worn tires.