I have the Vortex 6.5 x 32s, but I am not sure if they are the Viper model or not. I did a lot of research before I bought them, and it paid off------big time.
I have hunted with Zeiss 10 x 40s for a long, long time, but I have to say my new Vortex are brighter and sharper, and more useful for most bowhunting situations.
My Zeiss 10 x 40s are great for long-distance scouting, but for me, most of my use for binoculars is 200 yards and closer. Sure, I locate mule deer a long, long ways away with my 10 x 40s, but I can also do that with the 6.5 x 32s, but the 6.5s are far better at under 200 yards than the 10 x 40s, and the field of view is WAY WAY wider than the 10 x 40s, which is a huge plus if you wear glasses.
When you are trying to quickly spot an Aistralian wild boar's eyeball at 10 yards in the long grass to see if he is looking at you, or if you are looking into a brush patch at 20 yards to see if a mule deer is looking the other way so you can take just one more step, the 6.5 power and wider field of view is worth it's weigh in gold.
Don't get me wrong, I love my Zeiss, but for 90 percent of my hunting, I will be using my Vortex 6.5 x 32s. They are so bright and clear that is it hard to leave them at home.