I have 3.5x10 40 mm Leupold VariX-III scopes on my .25-06 and .243 which I use to deer hunt. My legal shooting hours in Oklahoma are 30 minutes before sun-up and 30 minutes after sun-down. I find that my naked eye loses the ability to discern targets due to low light at a point where the scope is still able to resolve the target and the cross hairs remain distinctly visible. Thus, in my particular situation, a scope with greater ability to gather light would not gain anything for me.

There is a relationship between objective lens size and magnification. Thus, if your scope magnification is lower, you don't need as large an objective lens.

Personally, I don't have any use for the big 56 mm objective lenses. The scope has to be mounted higher above the boreline. I wonder if the rifles mount as well or if you have to hold your head off the comb to line up with the scope? I suppose if you are moonlight hunting in the Bavarian woods for wild boar they might be needed, but not in my hunting experience.