I have used various .35 Whelen rifles for my "big" Canadian big game hunting for many years. Found them very effective, especially on elk. Our elk are usually hunted in early season when there is no 'tracking" snow, are more likely than most game to run with a vital hit. 250 grain bullets at 2500 FPS gave me confidence based on excellent results over many years. Quick kills, and even with a death dash, an exit wound could be expected to help with the short tracking job. But my adventures at home have become less adventuresome and somewhat predictable so my hunting interests have shifted to also include Africa. As a result I have recently been using both the 9.3x62 and 9.3x74 R, cartridges. They both have a solid reputation on African big game, whereas the .35 Whelen is almost unknown there. The results on game I've hunted appear to be pretty much the same. Both are able to efficiently take game bigger than you would think when looking at their modest ballistics. The thing I like about a 250 grain .358" bullet at 2500 fps muzzle velocity or a 286 gr. 9.3mm bullet at 2400 fps muzzle velocity is the ability to break big hard humerus bones and keep on penetrating to the vitals. .30 caliber or 7mm bullet just can't do that consistently.
So far I have used my 9.3's to take Elk, Bear, Kudu, Gemsbok, & Giraffe, with perfect results each time. I like the 9.3's.