It seems that some fragmenting lead and energy dump inside the buffalo leads to quicker kills over the mono-mentals and solids? Plus, less chance of over penetrating? Seems to be a plus.
I was surprised to read people use the Trophy Bonded Bear Claw TBBC on buffalo and it's success. Another bullet that could be a great buffalo round is the Federal Trophy Bonded Tip (TBT) is a thick base bonded lead core design like the TBBC but with a plastic tip and a bit more streamlined design.
I know moose are not buffalo but, from my own hunting experience in Alaska with the 300 RUM using the Berger's they have a much greater effect on moose after they're hit with that compared to the Barnes TSX. The Berger fragments and dumps it's energy inside the animal leading to a quicker kill. The moose reacts differently to Berger's as if it's been shocked and then it's legs buckle. I've never had a moose run off after being hit with a Berger but, they have run over 100 yards after being hit with the Barnes TSX on many occasions.