No worries. We only learn by asking the questions.
First, shooting the peeps on the Rugers is no problem at all. I do find the larger aperature easier to use in the brush and lower light conditions, as my eyes age. And yes, only the base differs to accomodate different mounting systems.
Second, light transmission on the scopes listed are good to excellent. While the older VX II (2-7x33) does not have as good of quality coatings on the lenses as the VX III's, today's VX 2 is yesterdays VX III, so are very good. All of these scopes light transmission capabilities lie in the mid 90's percentage wise (93-95% pretty much top performance available)
The biggest factor in scope brightness is exit pupil. Divide objective lense diameter by power rating setting and you will have exit pupil size.
i.e 20/5=4mm, 36/6=6mm, 36/9=4mm, etc.
The human eye's pupil can only dilate to 7mm in diameter under normal circumstances for a young adult. So a 36mm scope set at 5 power would provide you with an exit pupil of 7.2mm and provide more light than the eye can take in. As we age, our eye's pupil can only dilate to approx 5mm (approx 50 years of age), and less as we get even older, becuase the eyes pupil constrictors get tired and cannot fully open anymore. At that point, even if the exit pupil of a scope is 7mm, and the eye can only take in 4mm of exit pupil light, then that is as bright as one would be able to see.
So when I was younger, and my pupil could dilate to 7mm, I would set my 3.5-10x40 scope at almost 6 power (40/7=5.7) for low light shots across big fields to get as much light to my eye as possible. Now that I am 50, I would set that same scope, under the same conditions, to 8 power, as my pupil can only dilate to 5mm.
My mentor did a low light comparison test of a bunch of high end scopes several years ago (Swarovski, Zeiss, Leica, Kahles, Leupold, Nightforce, etc.), set to have the same exit pupil, to see which actually performed the best during low light conditions (first and last 15 minutes of legal shooting light). He found that the Swarovski, Zeiss, Leica and Leupold all performed very well and and at the same amount of light. He found the Kahles to resolve fine details clearer about 5 minutes ahead of the others. The Nightforce came in last place, and was over 5 minutes behind the Swarovski, Zeiss, Leica and Leupold.
Keep in mind, with the 9.3x62, for work in the dark timber, where short ranges are the rule, and not the exception, I will set my new-to-me Kahles 1-6x42 scope at the lowest possible setting so as to have a larger field of view to quickly track and find game in the scope at close distances. If I were to come across an animal at a further distance, say across a small meadow and in the timber on the far side, and I have time, then I would be able to crank the scope up to 6 power for more precise aiming through the brush. And while the scope would have a nice bright exit pupil of 7mm, my eye is only going to be allowing 5mm of light into my retina for brightness. And being a Kahles with Schott glass and an approx. 95% light transmission, I would expect to still see as well possible under legal light shooting conditions.
