personally I was not that impressed with the price oriented Viper scopes. Last year I picked up a Brunton 20x45-60 for about four bills to my door. REI had it priced for 650 but got it on line for less. It has many of the features you find on $1k glass including HD Floro glass, I have been very happy with it. Thought it had a better image than others in the price range (nikon, burris, bushnell, sequoia, viper, etc).
the one thing about it is it does get to be gray cast at dark45 plus, on high power. But I think it is more a function of the 60mm objective. put it side by side with a Zeiss, there was a sleight difference but it held its own.
Hope this gives another option-