Nice review, Ilya! Thanks!
I did a test drive of the Viper 8X42 and compared it against my Razor 8X42. Most of my impressions were the same as yours, with the following exceptions/additions:
- I thought Razor's sweet spot was much larger than the Viper. This may have been an illusion due to the overall more expansive view the Razor offers, though.
- I thought the Razor's center field resolution was a bit better than Viper. This was evident to me especially during star testing. Razor produced a more compact point of light than Viper.
- To my eyes, Razor produced a subjectively cleaner image, mainly because of the much superior CA suppression vs. Viper. Viper had fairly prominent yellow-green fringing around high contrast objects.
- Viper appeared to have slight greenish color bias, whereas Razor is essentially neutral to my eyes.
- Viper had more tunnel vision that I found somewhat distracting, whereas Razor produced more "enveloping" view, beyond the obvious FOV differences. But, I could live with that given its many other good virtues.
- Viper had a much flatter field than Razor, probably due at least partially to the narrower field.
- Even though Razor (newest generation, at least) has a nice focuser feel, I thought Viper's focus operation was as silky smooth as any I've ever experienced on a binocular, slightly superior to the Razor in that regard.
- I preferred Razor's center diopter adjustment on the focus knob over Viper's right barrel adjustment location. Just think optimal diopter setting was easier to arrive at in the central position and might stay put better due to the setting lock.
- My wife had a hard time getting optimal eye relief setting with Viper's eye cups. For some reason (eye socket and face shape perhaps?) that I can't put my finger on, she gets optimal view with most binoculars when the eye cups are extended nearly or all the way out. Razor had plenty of adjustment range, whereas Viper didn't to her eyes. This wasn't an issue to me, though, and I thought Viper's 4 position eyecups were adequate, thought not as comfortable to me as Razor's.
Viper is a very nice "compromise" binocular that seems to do everything pretty well, combining compactness, apparent ruggedness, and good ergonomics (at least to me) with good optics and reasonable price. I think it is an exceptional value and is hard to beat at its price! I felt Razor's better overall image quality and more relaxed view make it worth the extra price premium over Viper, but if I were looking for a compact 8X42 with the most bang for the buck, I would give Viper serious consideration.