I have to agree that a 300RUM kicks harder than a 375H&H but to say a 375H&H is easly managable? The 250 grain bullets have less recoil than a 300 grain bullet but flat out the 300 grain bullet just hurts. All that been said and if you really wanta 375H&H get it. Put a break on it and load it to the max. Should be able to stop a freight train. And it's kinda cool going to the range with something that has a hole in the end ofthe barrel that big.
If you're looking for overall useability the 300 Win Mag is hard to beat. It's not my favorite 300 but is very versitle. I guess the whole thing is kinda hard to answer because there is no real relation between the 300 mags and a 375H&H. The 375 is great for heavy thick skinned animals and will kill about anything you point it at. The 300 mags are great long range cartriges and will kill anything in North America. Just depends what 300 you would go with on how far it will efffectivly kill.
The answer is buy one each