Greetings MISportsman,
For what it’s worth, yours truly has used a simple and rugged Zeiss 4x scope on my .375 for many years, with perfect success.
That said, I no longer carry any firearm across international borders, as I grew weary of the red tape, extra fees and worry over potential vandalism and theft.
The safari company that I work for has a rifle identical to mine (Brno 602, .375 H&H) except theirs is equipped with a 2.5 to 8x Zeiss Dialyte scope.
It is my constant companion while hunting there with my friends and co-workers at Khomas Safaris.
I just leave it on 4x, so as to avoid fidgeting with the various magnification settings when instead, I should be firing that all important first shot.
Be all of that as it may, of the two scopes you listed, I think your Leupold 1.5-5x would be very good for your planned future Africa buffalo hunting.
It also would be just fine for all other Africa “plains game” critters, eland to dik dik, with the vast majority of hunting conditions in African countries where hunting is common.
For longer shots, across canyons, etc., on N. American elk, mule deer, pronghorn and such likes, perhaps your Leupold 2.5-8x might serve a little better.
But, I’d bet a large pizza that, when you are old like me and look back over your many adventures, all of the elk you ever shot, with your .375 and larger scope, would also have been easy breezy with the same rifle and your smaller scope.
Best Regards,
Velo Dog.