I like your post. I have the 35 Whelen and like it very much. I have read a fair amount on the 400 Whelen and it is very interesting to me. I think the 375 Whelen is a very good one too. Col. Whelen first started to work with what he called the 38 Whelen but the bullets were discontinued and there was not any good supply of 375 bullets at that time, so we got the 35 and the 400. As Michael Petrov said if there had ben a good supply of 375 bullets in the '20's we may not have the 35 or 400.375 caliber is a great mid bore caliber but I derive a wee bit more personal satisfaction by adding the spice of a wildcat. Three that I have tried in 375 caliber using the same basic case are the 375 Scoville, the 375 Whelen Ackley and the 375 Whelen. Of the three as a preference based on feeding characteristics not ballistics I have settled on the standard 375 Whelen. Perhaps not quite as energetic as a magnum non the less eminently lethal on big game. When loaded with a 375gn LFN of my design loaded to just barely shy of 2300 fps the load has proven itself a smashing (literally) success. A broad side shoulder hit at about 75 yards with the generous meplate of this long 375 caliber torpedo had the effect of completely knocking both antlers off a respectable bull caribou. Sounds like BS but gospel truth!
I also tried for a bit a 375 H&H improved in the form of the 375 JRS and it was a long range moose swatter to be sure but I just do not favor the additional weight of the magnum rifles usually having a more robust barrel contour than non magnum calibers.
Currently I have two rifles in 375 Whelen one for each type of hunting I might do with them. One is on a pre war Husqvarna with Euro style 27" barrel and scoped for relatively open country and the other on a1903 Springfield with 18" barreled carbine with receiver sight for close in timber hunting. Both rifles have coned breaching and controlled round feed so are quite dependable in feeding and extraction.
These are the enjoyable preferences of but one man but I felt might add a wee bit of spice to this discussion.