I don't own one personaly but friend of mine does. he's never killed anything with it except paper. I think that is liekly the cse for most people shooting that class of weapon, not that many lions runnin around where I live.
if you need a 375 class gun, the 375 ruger is modern version of the classic. It is a ballisic twin, ammo is cheaper, and rifles are cheaper and handier in general do to the shorter case. I almost bought one becasue they are so cheap, but can't justify it when I have other guns I want first.
I think you may have trouble duplicating the Hornady ballistics with handloads because they have been running some of the newer loading methods on these newer calibers (IE blended powders). I think you will easily be able to duplicate the 375 H&H ballistics because case capacity is nearly identical. TSX is as good a bullet as any, little pricey though.
Check our realguns.com, he has run extensive evaluation on this caliber.
I think this gun will stick becasue it makes sense and it is not just ballistic hype.