Speaking again from Asiatic buffalo experience, the front-on shot is a ripper if you forget about the heart and shoot high up under the chin. The bullet will smash the vertebrae at the base of the neck, where the spine dips down between the shoulder-blades, and dump him on the spot. I suspect this would be especially important with Cape Buff due to their propensity to charge when wounded, as the animal is already facing you and a fatally heart-shot bull can still run you over: they often bolt flat-out when hit in the pump.

If you look at the illustrations provided by Bob you will see that the front-on spine-shot offers quite a large target, about the same size as the heart anyway. Also, they often lift their chin and point their nose out trying to get your wind, which makes the shot even easier. I have used this shot a number of times on big bull water-buff with Woodleigh softs and it is spectacular, to say the least! Can't imagine why a PH would discourage it.