I've hunted only with an H&H, although loaded and tested ammo for a friend with his .375 WTBY and compared our results. There is no difference on game from drop or killing power and either shoots flat enough for 300 yards, beyond which, I believe, no one should be shooting at big game.
: Indeed, even the smaller .375 Scovil or .375/06 IMP does as well, with it's loads in ozhunter's range.
: There is realy no advantage of going larger cased than the .375 Ruger or .375 H&H.
; The Improved case's life-time may be longer, but I got over 12 loadings from my 200 .375H&H original brass and very few guys do that much shooting with their big bores. I used mine for coyotes and ground squirrels to learn how to shoot it accurately. It was good practise.