I shoot a .375 a lot and we’re it legal, I would rather use a 250 gr .338 on a buffalo than a 235 gr .375. Such a light bullet defeats the purpose of such a splendid all around caliber. I frankly feel the same way about a 270 gr bullet. The caliber is one of those rare wonderful things that doesn’t require over thinking. Load it with a quality 300 gr SP and go hunting. All my buffalo have been killed with either the 300 gr TSX or Swift A-Frame. None went farther than twenty yards after being hit. They worked equally well on every PG animal I took on the same hunts except for a few of the tiny fellows shot with 300 gr solids. And the trajectory is perfectly adequate for any shot any competent PH is going to allow his client to take.
As you note, charges are extremely rare, but if I have to potentially penetrate an inbound boss, I would much rather attempt it with a 300 gr. Bullet of any construction.
If you show up in Africa with 300 grain Swift A-Frames, your PH will be delighted.
Demonstrate to him that you are capable of shooting it out to 300 yards with accuracy and he will be elated.
I took everything from Blesbuck (200 yards) to Eland (100 yards) with the 300 gr SAF and nothing went very far.
After speaking with my PH, he said that the 375H&H 300 gr SAF's are good for Buffalo as long as you do your part.
I also asked him about taking solids for a follow up shot and he said it would be fine if I wanted to bring them, but it wasn't necessary.
To that end I'm working on solids that will shoot to the same point of impact as my SAF's.
Do your part and make that first shot on the Buff (or any animal for that matter) count to minimize the chances of a charge.
Dealing with a charge is a real thing and being prepared is important.
That being said, the job of a client and the job of a PH are very different.
Sorting out what to do in the event of a possible charge would fall into the hands of the PH, so just do as he asks you to.