I know this is boring, but a .375 is just about the perfect choice for a client. Moreover, it is not merely a compromise. It handles everything well. I either own or have owned a .404, 500-416, .470, .416 Rigby, .470 and .416 Rem. I shoot them all well. I have actually used a .375 exclusively. It is a joy to carry, and with a quality 300 gr bullet it will handle everything from suni to elephant (and yes, most of us probably would use a forty something for elephant, but I suspect more clients have used the .375 successfully for such work over the last 50 years than all other calibers combined). For a new DG hunter in particular, it is a very easy transition from a familiar deer rifle.