I've owned 375 WINs in Marlin, Savage, and Winchester/USRA lever actions.
I reloaded for the Marlin and Savages and liked the 220 grain Hornady better than the 200 grain Sierra.
I have come to think of the 375 WIN as a more expensive and more difficult, because of the lack of component bullet options, way to get the same performance as the 35 REM.
Hmmm... Maybe I'm not comparing apples to apples. A 35 Rem would do what I want to do, but comparing Winchester ammo info, I'm seeing across the board approx. 200 ft/sec more velocity and 300 ft/lbs more energy out of the 375 Win over the 35 Rem. Comparing 200 gr bullets in both. Agreed that's not an astronomical difference, but at the speed these bullets travel, we're talking approx. 10% and 15% differences, if I did the math right.
Lack of components or the cost of a box of ammo is a big difference.
I don't know how ft/lbs are calculated, but the 180 fps difference in muzzle velocity and 0.017" difference in bullet diameter doesn't seem like it would make that great a difference in either calculated ft/lbs or actual down-range performance.
X35R1 is Winchester/Olin's lone 35 REM load that has a claimed 2,020 fps and 1,812 ft/lbs at the muzzle.
X375W is Winchester/Olin's lone 375 WIN load that has a claimed 2,200 fps and 2,150 ft/lbs at the muzzle.
The 35 REM and 375 WIN are physically quite different, but performance wise they seem more alike than different.
A couple of tangible advantages that the 35 REM has over the 375 WIN are as follows:
1. 35 REM factory ammo is a regular production item from FED, REM, and WIN. 375 WIN factory ammo is a seasonal run item that is only produced by WIN.
2. 35 REM factory ammo is widely available, particularly in the northeast, while 375 WIN ammo is quite uncommon.
3. Far more rifles have been chambered in 35 REM than 375 WIN, so they are much more common and generally less expensive.
I still have several boxes of both 200 and 250 grain Winchester/Olin 375 BIG BORE ammo squirreled away somewhere.
In 1987 I took a small buck in Cornish, NH, with 1 shot from a Savage 99 Brush Gun using 200 grain BIG BORE factory ammo. The shot was taken at very short range, no more than 25 yards, and the point of impact behind the shoulder knocked the small buck over, dying in its tracks.
