Can you elaborate on the "why" here? Is it just a field of view thing?
It is hard to answer questions on forums as everyone's needs are different and why I recommend that I speak to a person about their individual needs. However, on Forums I have to try to speak in generalities. My comments were addressing general needs, but they vary depending on many factors including terrain, target species etc. For example, for hog hunters who want to stalk hogs, they may want a long-range scanner to tell deer from hogs from the truck, and then stalk in and shoot with a wide FOV scope because they are stalking into close range with many hogs in a sounder. Whereas most coyote hunters want a wide FOV of scanner to see them coming from any direction while calling and then shoot with a little more magnification as their shots may be longer and more singular or a few animals vs a large group of hogs.
The simple answer is it is totally a FOV and base magnification thing. With everything else being the same, a 25mm lens has less of a focal length, so it ends up having a wider FOV and lower base magnification.
Vibe 25: FOV 14.9° and Base Mag 1.4x
Vibe 35: FOV 10.7° and Base Mag 2x
Super Yoter 25: FOV 18° and Base Mag 1.5x
Super Yoter 35: FOV 11° and Base Mag 2x
Phenom 640: 13° and Base Mag 2x
Thing is, I may be able to get a 1 year old SY35 for slightly more than a new Phenom 640. They're both 2x, and while I can see that the Phenom has a wider FOV and I assume the ergonomics are a little nicer, it's limited to one role.
Yes, the Phenom has a singular role. It cannot be used as a scope, only a scanner. So, if you need a device to do 2 things, the choice is easy. For coyote hunting, I will always need a scanner, so for me I buy a scanner. If my purpose could be 2-fold, then maybe I would consider. I already mentioned scanners are typically cheaper, and yes they will have better ergonomics for holding or transporting it. There are lots of people using compact scopes as scanners, and if that fits your needs, that is great.
Side question: are all the mounts on Bering scopes epoxied on? -- I think I'd want to remove that for a handheld role.
Yes, they are epoxied on. What some people do is use a selfie stick and tap a hole in a picatinny rail or riser and then mount the Scope with picatinny mount right on the pic rail of the selfie stick. This takes the fatigue off your shoulder and make scanning easier. If you are wanting it for a dual-role, I would leave the mount on.