I don't envy you.. Picking bino's as you seem to know is tough. It's something you use a lot, and yet have for a very long time. Buy once, cry once, and get the best you can.
I was going through the same issue a few years ago, and found what i thought was a good solution:
I went to the local Bass Pro, where the atrium of the ceiling used natural light for the store. At one end was the optic counter, and along the walls was stuffed animals on ledges across the whole store. maybe 75yrds.
I went in there after sunset in the low light, and tried all the differnt kinds. I would look at the animals in the low light and see which was clearest, and had the most crisp image. I tried to fog the lense and then look again. I looked for 10s and then after doing that i tried a set of 8s. I was very surprised at what i saw and after thinking about it, and what i am doing with them. I picked the 8s.
I then had the wife come over.. She has no idea, she has no name brand recognition. So i let her look at everything and look at the animals, can she see the hair, the eye's clearly, the tongue sticking out. So on..
I had her lay them out in order of clearest to worst. I was and wasn't surpised when she said that Skis were the clearest. Not a surprise. But, she said that another pair was very close and she wasn't sure which she would pick. I told her the prices of both and there wasn't $1000 differences. SO.. I picked and have been really happy.
As for the 8s vs 10s, unless you are sitting on a hillside spotting deer or Elk often, I can spot Elk and for that matter Coyotes at more than 1000 yrds without issue, so I don't think 10s are worth it, and i scan every stand within 500yrds of me before calling a stand and taking off. More than a few times i have spotted a coyote or bobcat standing next to a bush i would have otherwise missed. The first two bobcats I shot were becuase of the bino's and they ironically paid for the glass. Big bino's weight more, and after days of hunting, it's got to be worth it, or your just hauling around more weight.
