I don't mean to open up a contentious issue, but the mechanical versus fixed blade topic is particularly relevant to Africa. The GOAL is so important to considering the right tool for the job.
For the small stuff: (warthog, duiker, grysbok, klipspringer, springbok, bushbuck)
1.) Does it fly absolutely true?
2.) Is it the fastest setup you can possibly make?
3.) Penetration doesn't matter, its happening in excess.
4.) Blood trailing doesn't matter... it's gonna bleed. (and the trackers in africa WILL find it)
In light of that, Mechanicals have a few problems. Sure, when they work, they work amazingly well, better than any fixed blade. And when they don't work well? They fail horribly. They can cut on the two angles that you didn't want them to cut, they can open asymetrically and re-reoute your arrow, they can open after entry (no entry wound) and stop under bone (no exit wound).
Depending on your arrow setup, you might want a razor-sharp 75-85gr two blade fixed, perhaps with a bleeder. Whatever it takes to build an arrow that flys like a bullet.
For the big stuff, no one has EVER said mechanicals are the way:
1.) Heavy FOC
2.) Slow, heavy arrows for deep penetration
3.) Cut on contact for immediate bleeding
4.) Two blades for further penetration
Hell, for the big stuff, its not unreasonable to spend $100-$150 PER ARROW to build these setups. For the small stuff, you want to find the "hogwash-bs-no one in the USA uses them" arrows that all the manufacturers use to brag about how fast their bows actually are. Then you want to improve those even more if you can.
The one truth about Africa that never fails to hold: Whatever we believe is true about big game hunting in North America, whatever gear is great, whatever gun is awesome, whatever scope is the best, whatever bow setup is ideal....it's all wrong for Africa.