My thumb is neither long enough nor strong enough to get both hammers cocked on the rise, therefor I cock both hammers and often hunt with the action open but I tend to agree with Jawjadawg and Eightbore. I'll often be found in the coverts with the action closed, hammers back, and two fingers across the trigger guard bow to prevent a stick from touching the triggers but anything can happen I suppose, in spite of how safely one believes he hunts... even with a hammerless gun.
It is up to each man as to how he will hunt with his hammergun. Gun safety must be the preoccupation of each hunter and consideration of his companions, two-legged or four, must always be given.
If a man chooses not to hunt with me because of how I carry my hammerguns, that is his choice... but he can't accuse me for a moment of being 'unsafe' - his safety will always have been my first consideration.