I'll write this very humbly, and just try to describe some recent observations.
On a recent DG hunt, my first one, I had brought my .416 Rigby bolt-action, with its sling. Intending the rifle to hang from one of my shoulders at all times. The PH's instructed that when we left the truck, I had better be loaded up, round in the chamber and safety on. No more noise, fiddling around trying to chamber, or other things to go wrong. Just be ready to take a shot.
When the tracking of the DG was happening, while stooping forward, moving around brush, climbing up rocks, avoiding branches from all sides, I went out of my way to keep the rifle from pointing to anyone. Having the rifle hanging on my shoulder was a true PITA, as I (or the sling, or the rifle barrel or...) got caught in too much thorns, shrubs, branches and what have you. So usually when the vegetation was too thick I would rather keep the rifle in my hands, so I could move it up and down, from vertical to horizontal, all the while snaking through the brush, I did all I could to keep the barrel from pointing to someone, but was failing often (and cursing myself for it), this happened especially when the people in front were not going in a straight line, while I was trying to avoid brush. So when one moment there was no one in front of my barrel, suddenly someone had walked in front of it.
Both Zim PH's, one carrying a 458WM and the other a 500 Jeffery, were fully loaded, round in the chamber, safety, without a sling. Meaning they were using the African-carry. I cannot remember the number of times I was pointed a barrel at. (nor the number of times I pointed a barrel at someone). We all did our best, this could be easily seen through how we behaved, to consciously try to avoid it happening, but happen it did nonetheless.
Carrying a heavy .416 rifle in your hands through bush, get's heavy after a while, especially while concentrating on not making a sound, not getting caught in thorns etc. So I tried the African-carry style. (I even explicitly asked the PH if he would be comfortable with me doing so. Fully loaded, round in the chamber, safety on, african carry. This was after a few days of having hunted together, and he nodded his okay). Trying this way of carrying, was a big relief through brush. Suddenly I could be much more nimble moving through the thorns, I was less getting stuck. I still made it a mental point to keep that barrel pointed away at all times from anyone else. But still failing sometimes. As soon as we came on more open terrain, back went the rifle on the shoulder strap. (Over the entire safari, this was its location 90% of the time, when away from the cruiser).
All through the safari, whether hanging from my shoulder, or in the African carry, I would be checking the safety being back still, touching it to make sure, every few 100 steps.
Now to contrast, someone very close to me, when hunting in Belgium, or once in Africa, has an awful sense for safety around firearms. He knows better than everyone. He'll unload a bolt action, with the barrel firmly pointed at someone's chest. He'll be walking around, or moving about with a firearm, loaded, round in the chamber, safety off, pointing it everywhere (including his own grandson's...). On top of that he does not have the nimblest fingers, when he reaches for the pistol grip, he tends to immediately put a finger on the trigger. Once in Belgium, once in Africa he has had an ND because of this. The only reason no one got hurt, is because he was lucky he had the barrel pointed somewhere where nothing serious could happen. (not because he consciously had the barrel pointed somewhere safe, one round went straight into the air, while he was crawling through a field, with a guide next to him)
This long story to say that I am by nature a very punctual, precise and safety conscious guy. Always minding where my barrel is pointed at, using my safety at every turn. If not necessary to be loaded, I unload. etc. Even though I fail (often) at it (or in the case of the African carry recently, going against what I would prefer, but was dictated by the circumstances), I am very aware of what I am doing. In contrast, this other person, for whom safety is something for other people to worry about, as he knows best.
I would much rather be with those two PH's, african carry, fully loaded, safety on, all year long, and I would (now) trust myself with it as well, than spending one day hunting with someone, who is not safety conscious at all. Because for the latter, even if there shouldn't be a round in the chamber, even if the safety ought to be on, even if the gun or rifle should be broken open, there will be moments that they do not pay attention. Because it is their nature not to pay much attention to this.
So, I agree with the camp that the best safety is between one's ears. The mechanical safeties are just bonuses. What I wanted to make clear, is that I am less against african carry than I was before, if it is the right safety conscious people doing it. But it is definitely not for everyone. In fact, I still would not recommend it.