Good point on the frontal shot. What if he is charging across your front at your wife? (assuming you would shoot at all in the case)

I think most charges are not aimed at everyone there but at only one person and thus only one person has the perfect angle for a CNS shot.

If you think carrying a 400 is adequate because you are only going to take a frontal CNS shot than what would you carry if you were going out alone or with only an unarmed tracker?