I think the cocking safety would be wondrous on a break action single shot. Not sold on the Double Rifle though as I think you need to be able to use it unconsciously and if you have other Doubles you shoot you could get confused at exactly the wrong moment.

I lost a very nice Deer once because I was not familiar with the safety on a Mauser, having only shot Winchesters at that point. I couldn't find the safety with my thumb without looking and I spaced on the actual location for just enough time for the Buck to make a jump and he was gone.

At least it wasn't a charging Ele.