I would say the 9,3x64 never will be very popular for a few reasons. The kind of performance is not needed for most European game. In African countries where 9,3x62 is legal to use in some African countries while in others 375H&H is the minimum requirement. 9,3x64 falls between these. What is the point of 9,3X64? There is just one maker of ammo, RWS and hardly any rifles chambered for it.

I like the .375 will be a 375 Blaser magnum, no pesky belt and better performance at lower pressure etc. than 375 H&H.