I've done all of the above for years. Frankly, when I'm traveling, not hunting, I use a Kifaru Gun Bearer only if I need both hands free. I might be using trekking poles, or I might be doing some standing glassing, etc.
I've done lots of quick shooting with a rifle sling. If you carry it upside down, muzzle down, it comes up and gets on target just as fast as the Woodsman Carry, i.e. cradled in the weak arm.
A properly adjusted shooting sling will cut your group size at least 30%. That's why all of my hunting rifles have sling swivels and a sling setup for each of them.
While the military style shooting sling tends to be slow and can cause some fumbling, the CW setup reduces speed not one bit. That's why all of my big game rifles have them.
I find it very advantageous to use a sling, african style, muzzle down, while tracking or still hunting. That allows me to use my binoculars to look through cover and, hopefully spot him before he sees me. If I can do that, I get to shoot him in his bed or as he gets up casually for a look around. Not when he suddenly breaks cover and gives me just a few seconds to shoot. The toughest shooting I do is on game that takes me by surprise and gives me seconds to shoot. I'd much rather see him first and be able to take my time, or at least be fore warned. E
