Have never seen them used on Cape buffalo, but have seen Woodleighs in calibers up to .416 used on other game--and the few African PH's I've run into who have any experience with Woodleighs said they worked well.
One virtue of even the heavy Woodleighs is they open so widely they don't tend to "over-penetrate." which when hunting buffalo in herds can prevent a bullet exiting and wounding a second buffalo. Thee wide expansion also results in a big wound channel, which usually kills quicker. On the other hand, have also seen a .416 340-grain stop in a 100-pound fallow deer doe, on an angling shot from the right rear of the ribs to the left shoulder.
