I just picked up the viper. It seems to be a gen 1 Razor for all intents and purposes. I haven’t gotten to compare it with the razor in low light scenarios. I did compare them mid day, I found them both to resolve equally. I spent some time with the viper in the evening hours on its own. The viper darkens up at 30x plus. Missing out on some magnification, but I love my 12x Binos on a tripod, so the spotter is just there to check legality/see if I want to lace up and head after something. 98% binos/2% time behind a spotter. With a scheels gift card I didn’t see the need to spend the extra 500 bucks. If you spend the extra cash for the razor, why not save a little more and grab a Kowa, if you have cash for the Kowa…. Etc. I do prefer the dual focus knob myself.
TLDR: I wanted to not like it and liked it quite a bit. I wouldn’t shy away unless you are vortex phobic.