I think it's fair to call the .375 a "medium" bore when talking expressly about big game rifles only.
Owning a gun like the .458 or .500 Jeffery that necessitate a change of pants after the first shot might sound good in theory (?) but if you have no use for it you're probably better off without it. Downloaded with cast projectiles they are more than manageble and most people I know shoot them like this to get used to the rifle and how it handles. Shooting at a buffalo with your adrenalin up, you're not so likely to notice the recoil from a full house load.
But if you just buy one and don't have any buffs or elephants, shooting those full house loads at paper is going to leave you with a flinch that will take a lot of concentration to get over - and it will probably ruin your trigger control for the other guns you shoot too, at least temporarily. I know maybe two people who can shoot the really big guns well, all the time - the rest are just human like me...