You guys hunting birds with open doubles are hunting different birds than I hunt. If nothing else, I'd get too much debris into the clockworks of my Citori if I hunted grouse with it open like that.
The folding BLR hammer is a brilliantly safe design for an open-hammer gun. Even IF something somehow got between the scope and the rifle and hit the hammer and knocked it off half-cock, the hammer covers and protects the firing pin. By my (non-MechE) analysis, for it to fails gets into the shear strength of the large steel pivot pins and the receiver itself.