Maximus, this is entirely down to one thing I can think of, .375 flanged and 9.3x74 are ballistically almost identical BUT if you are taking the rifle to Africa in a lot of that part of the world, one is legal, the other not ! Both are available in Europe, Norma load the flanged .375, many companies load the 9.3 but you are not going to find either in Africa so availability is neither here nor there, I would get the .375 flanged and buy 1000 rounds of Norma ammo just in case they cease it !

best, Mike