Never been to Africa, but I have accounted for an Asian water buffalo or two over the years. At this point, I have never fired a solid at a buffalo. I believe your observation about modern premium bullets is correct, especially the bonded-core softs like Woodleighs.

I Africa though, solids for follow-up shots may be advisable in certain circumstances, but for the first shot on buffalo I believe a premium soft-point would be the best.