The 9.3X62 is an outstanding shell. It works best with a fairly tough bullet. I have used the 270 grain Speer with much disappointment, but the Noslers and the Barnes, and to some extent the Hornady bullets all work well.
Brass can be made from 30-06 but it is not quite to “spec”. It usually works fine however. Hornady makes correct brass, so there is not a real need to make it from 06 brass
With correct bullet that don’t break up, the 9.3X62 will do nearly everything a 375H&H will do, and it does it with less recoil, more magazine capacity and usually a light rifle.
It’s simply one of the great cartridges