As you compare the .318 WR to other cartridges in the same class like the .30-06, the .338-06 and others, IMHO you miss a near twin: The nearly (in Germany) forgotten "Versailles-treaty cartridge", the 8x60S aka as 8x60 Magnum. I have to look hard to distinguish between the two. The photo shows, l to r, the following loads:

.318 WR, old Kynoch, 250gr soft nose
.318 WR, old Kynoch, 250gr solid
8x60S, hs "Browning", 225gr soft nose
8x60S, old RWS 225gr solid
8x60S handload, 53 gr VV N140 behind a .323" 250 gr Woodleigh soft nose, instrumental velocity from the (shortened because of muzzle damage) 23" barrel of my 1929-vintage Mannlicher-Schoenauer 710 m/s = 2330 fps. A German "authority" wrote that this bullet will not stabilize properly in German 8mm barrels. Well, original pre-WW2 8x60 commercial Mauser sporters featured a 1 in 12"twist. But the barrel of my Mannlicher-Schoenauer has a very rapid about 1 in 8" twist and it shoots this bullet just fine.

Next is my standard 8x60S handload for use on our lighter German game: a humble 200gr Speer softpoint in front of 50 gr VV N140 for 787 m/s = 2580 fps. This load killed a truckload of game for me. Yes, these velocities may appear to be inferior to the New-Kynoch .318 factory numbers, 250 @ 2400 and 180 @ 2700, but Kynoch uses a 28" test barrel! Try to find a 28" barrel blank nowadays. So I think my 8x60 loads are equal to the .318 ones. IMHO it will take a very sophisticated hunter and/or animal to notice a difference in actual use.
Last cartridge in the lineup is, for comparizion purposes, a 30-06 with a 220gr Hornady.