Damn, Petzl publishes two different recommended techniques for the Grigri. They warn the user that both techniques have recommended positions that are sketchy and should not be held for long. They publish skull and cross bones on techniques that we SEE AT THE CRAG all the time. On top of these hypothetical issues, climbers are dropping too frequently. What the hell is the fix?
it's not the device or the method that matter. when your climber weights the rope make damn sure your break hand is on the brake side of the rope and in the appropriate position to create enough friction to stop the fall. most of us choose to do this by keeping a brake hand on the brake rope all the time, but obviously there are tons of small variations on the belaying theme that are practiced successfully every day.
"Most men lead lives of quiet desperation." Thoreau
all i'm saying is that every one of these accidents would have been prevented if people just put their brake hand on the brake side of the rope below the device and squeezed (again, assuming the right amount of slack was out). nothing else really matters. it was their inability to do this that caused the accidents and everything else is avoiding the point in my opinion
"Most men lead lives of quiet desperation." Thoreau