Re: 50mm or 56mm is it bright enough to make it worth it???
Not only that. How much light can the human eye benefit from? When looking through a 1" tube, how much light can my 40 year old eye gather? Is there a point of diminishing return on a larger objective, and if so, what is it? 44mm, 50mm, 52mm.
As I see it (haha), every eye is different and will perceive things differently. To me, the biggest disadvantage of mounting a high scope is the cheek to stock weld.
When I close my eyes and shoulder my shotgun, I can open my eye and be exaclty on my sight plane. Very little, if any adjustment of my head is necessary. Some will argue that this type of fit is not necessary for rifle and I don't totally disagree with that. Afterall, snap shots are rare and mostly ill advised when rifle hunting.
Still, I like to shoulder my rifle and have a good fit of cheek to stock. If a gun doesn't fit me right, or the scope is too high for me, I don't shoot as accurately. And seeing game only helps if you can hit it!