I see the leg loop backup as overwhelmingly in case of getting clocked by a rock, losing grip on the rope, etc .. all likely occurrences ... and only minutely in case of abseil device/attachment failure, which almost never happens ... poor Todd excluded.
Other good thing about leg loop linkup is that said knot (yes I also use a klemheist) only has to take the weight that your hand normally takes. If knot is above device, it has to take full load of your bod. And it tends to lock up, as Manacubus correctly observes... |