Pneumatic, great post!
1. I never watched the BMW freefall vid close enough to see what was going on. I just assumed it was ABS not allowing a lock-up by not braking. I see his right foot is off when he starts moving... tho GS brakes are linked, too - maybe a factor.
2. My own (tame) experiences with ABS on loose stuff is that it does better than I think I would. The stress of feeling ABS kicking in on gravel is mitigated by how well it's worked for me.
3. The clutch idea is a great idea, and not something I would think of sitting at the top of a hill. With the engine off, won't I lose my power steering, too, tho? :biggrinjester:
One of my scariest moto memories is having gravity alone pull me down a long, STEEP city street with fresh gravel on a KLR with both wheels locked. I don't think I ever topped 5 mph, but it feels like 100 when you can NOT stop. I slid right thru 2 intersections... probably 100 yards or so... stopping only when I hit level ground at the bottom.