Yep, I firmly believe one of the reasons Cape buffalo acquired such a reputation for being hard to kill is the widespread use of solids (especially in the .375 H&H) before so many controlled-expansion "softs" appeared on the market.
The only experience I've had with .458 caliber cartridges on Cape buffalo was watching people who accompanied me use them, including PH's and hunting partners. Only solids have sucked: Unless one hit the brain or spine, or broke both shoulders, buffalo pretty much kept doing their thing, often for quite a while.
That includes a bull one of my hunting partners shot while after elephant, and all he and his PH had along were solids. He and his PH chased it around for several hours, putting several flat-nose .416's and .458's through chest-cavity vitals without much effect.
So far every modern soft has worked well, including Barnes TSX's, Nosler Partitions, Swift A-Frames, Trophy Bonded Bear Claws, etc.
