I am going to take a minority opinion, based on my limited experience of two trips. First trip was 30-06 & 375 H&H; second was .338 Win and .416 Rem.
1) Once an animal bleeds, you have paid for it. With lots of trophy fees north of $1000, I don't want a "get by" rifle/bullet.
2) Most shots are 250 yards or less, meaning trajectory minimization through velocity is not a significant goal.
3) I like two holes in critters to improve the tracking-recovery odds (see #1 above.)
4) Getting a rapid second shot off is important (and PHs say this is a skill American hunters are typically weak on.)
5) Sometimes you are walking around Africa feeling a bit more like the prey than the predator.
So I like a bigger caliber and heavier/slower bullet combo--it just makes me less nervous in a number of ways. For me, .338 Win loaded down a bit (like 100-150 fps off max) to take the edge off the recoil is perfect.
But a bigger issue is probably the scope. A 1.5x-6 is about ideal. Go to Africa with a high magnification Hubble and you will regret it more than cartridge choice.
