I hunt a lot of quail, and I have never been asked to walk up to a covey with an open gun. Were a guide to require that, I would find another guide. Likewise, I am not going the walk about dangerous game country with an unloaded double. I should note that I have never been asked to that either.
There are basically two types of safeties employed in doubles. I'll come back to the K-Gun in a moment. Trigger blocking safeties are the cheapest for the gun manufacturer and least "safe." They do exactly what the name implies. They can not prevent a hammer slipping from a sear and falling due to a dropped firearm or something similar.
Intercepting safeties, intercept the sear preventing the fall of the hammer under almost any conceivable condition when engaged. Such safeties are easy to spot on most boxlocks by the small pin (screw) on either side of the upper edge of the action fence.
As
@1peggy correctly notes, the cocking slide on a S2, R8, and K-Gun is, with just a bit of practice, is about as easy to manipulate as any other gun while bringing the rifle to the shoulder.
What really puzzles me is why anyone would carry a rifle differently in Africa than he does in North America or Europe. That vast majority of us use slings and we have trained ourselves well to be very careful managing our rifles while using one. Why on earth change to go follow a cape buffalo? I frankly think the African carry is more about looking the part than any practical value. In Africa I carry my S2 just like I carry my R8 Muzzle down over the left shoulder - left hand on the forearm. It comes up instantly and is always out of the way of brush. A rather well respected PH by the name of Len Taylor uses the same carry.