The difference between the 375 H&H and the .375 Ruger are almost identical to the differences between the 300 H&H and the .300 Win Mag.
Alaskans are voting with their pocket books and the Ruger is currently outselling the ancient H&H by a wide margin and a number of astute African PH's are also discovering the benefits of the Ruger as well.
And when I get a spare ZG47 it will make the transition to .375 Ruger.