For Cape buffalo, I'd rather use the 416 Rem. Mag. that either the 416 Rigby or 375 H&H. As fas as I'm concerned it's a much more sensible option that either one of them.
You can have a 416 Remington rifle that is the same size and weight as a 375 H&H and with the same magazine capacity, yet delievers 416 Rigby ballistics and kicks significantly less due to the fact that it burns 25% less powder.
It's the best of all worlds............
AD