To answer your question about comparing the recoil to other rounds...

Assuming that all three rifles weight the same at 9.25lbs, here's how they stack up with what I believe are typical loads at roughly the average published velocity for that bullet. The data was taken from the Hodgdon load data on their website.

The junior member of the trio, the .338 Win Mag, shooting a 210gr. bullet at 2850fps with 67 grains of powder will produce 29 ft-lbs of free recoil energy at a velocity of 14fps.

The .375 H&H, with a 300 grain bullet propelled by 78 grains of powder at 2600fps will slap you with 44 ft-lbs at 17fps.

And the bruiser of the bunch, the .30-378 Wby. Mag, shooting a 180gr pill over a whopping 110 grains of powder at 3400fps will sock it to you with a bone jarring, tooth cracking, retina separating 54 ft-lbs of energy at 19fps, and that's with the lightest bullet the data provided. With the long 220 grain Nosler Partition the recoil goes up a touch to 56 ft-lbs and 19fps.

So the .30-378 has 18% more free recoil energy than the .375 H&H, and 46% more recoil than the .338 Win Mag in the same weight rifle.

If you compare the trajectory of the 30-378 to a milder and more practical 300 magnum like the 300 WSM, you'll see that there isn't much practical difference at hunting ranges, which I'll say maxes for all but the most talented marksmen at 400 yards.

If the two cartridges fire the same 180 grain bullet (180gr. Hornady SST with a BC of 0.480) at velocities typical of the cartridge, 3400fps for the 30-378 and 2950 for the 300WSM, the trajectories are as follows (250 yard zero):

30-378: 100: +1.76", 200: +1.56", 300: -2.61", 400: -11.33"

.300WSM: 100: +2.66", 200: +2.18", 300: -3.62", 400: -15.58"

So the difference in trajectory is a mere 1" or less out to 300 yards, and only a touch over 4" lower at 400 yards.

The 300WSM, with a lighter 7.75lb rifle and 65 grains of powder will hit you with a still stiff 30 ft-lbs at 15fps, but with a rifle you wouldn't mind humping around all day.

Mike