Vern, I'd beg to differ.
For example, Winchester's domestic loading of the 8mm Mauser gives 2360fps for their 170gr version of the round. Winchester's 165gr loading of the .30-06 Springfield gives 2800fps. My Burroughs Adding Machine Math gives me a velocity difference of 440 fps. That's just a smidgen more than the 100-200 fps difference you posted.
Just for grins, Winchester's 170gr loading of the .30-30 Winchester gives 2200fps.
So what does this tell us?
1. Domestic 8mm Mauser ammo is horribly underloaded, actually closer to .30-30 Winchester than .30-06 velocities.
2. .30-06 ammo may or may not be reduced in deference to low-number Springfield rifles, but not by much, compared to the downloading of 8mm Mauser ammo in deference to '88 Commission Rifles.
3. SAAMI is the long pole in the tent with respect to commercial 8mm Mauser ammo.
4. The 8x57JS round is quite efficient when loaded to proper capacity. S&B sells their 196gr round, which move out at 2589fps, not too shabby for that bullet weight. In contrast, although I don't see too many .30-06 commercial loads with that heavy a bullet anymore, King's Custom Ammo does sell a 200gr GameKing .30-06 load, moving at 2360fps. I'll assume the latter is hindered by a SAAMI-style hitch-in-the-git-along.
5. Cosmo and I have gone around about the .30-06 being underloaded and inefficient. In 2005 terms, maybe so. But not in 1906 terms, and certainly not in 1938-1945 terms, with respect to the M1 Garand, BAR, and 1903A3 Springfield rifles. Propellant technology has come a long way since 1906, witness the ball powder innovation that gave the .308 Winchester/7.62mm NATO .30-06 performance in a case that's 1/2" shorter in length than the parent .30-06. High velocity with low pressure is the holy grail of ammunition manufacturers. Watch the velocity to pressure curves of a given round through the years, and assuming the liability lawyers don't arbitrarily clamp down (ie, the changes in .357 Magnum top loads over the last few decades), you'll notice the improvements.
6. I think a variant of the 8mm Mauser, probably in .30 caliber, like a 7.62x57, would end up as our service cartridge were the .30-03 or .30-06 not selected by the War Department.