I've recently got to test the Vortex 50mm 11-33, Kowa 55mm 15-45x, and Meopta 15x56 and Maven B5 18x56 in mountains. I went back and forth on the spotter vs high mag bino debate. I can tell you a few things that I learned.
First, you get what you pay for. Comparing an expensive bino vs a cheap spotter, or vice versa, the more expensive piece of glass will be more impressive.
However, unless the price point is extremely uneven, each will always be superior to the other in different ways. The spotter will always be able to resolve more detail. If you need to make this investment to see small detail or very far away, the spotter is the best direction. But, if you don't need to, say, count moose brow tines, judge full curl sheep, or count points, and finding the animal at great distances is the great challenge for your hunt circumstances, we two-eyed creatures will be much more effective looking with both eyes. Even at a lower magnification.
I think for the above reason, is why so many are so certain in either direction. It really depends on the nature of the hunt. For me, in Alaska, bull moose, sheep, even caribou are fairly easy to find with 8 or 10x binoculars, then I want as much magnification and large diameter scope as possible to judge the legality of the animal. But if I need to sift through a valley for an animal this is camouflaged, I'm going to need a system to use both of my eyes to distinguish the slightest 'off' looking thing.
Out of the two spotters and two binos I mentioned at the top, I ended up keeping just the Maven 18x's. They're such a joy to look through for long periods and incredible to pick apart a landscape. The Kowa 55mm did show greater finer detail, but I decided that when I do really want to see that detail I would rather just pack my big Kowa 88mm.
