I haven't had the chance to look through a Viper, but I did purchase the 11-33x50 Razor last week. I tend to prefer better glass vs extra objective size and increased magnification, but others may have a different opinion. I purchased the scope for range use out to 400 yards, and to have a lightweight compact scope to take out west to view game up to about 1-2 miles. So far, I haven't been able to test this scope beyond 500 yards, but I have been impressed with its performance. Yesterday evening I was reading the license expiration tag on a vehicle parked about 390 yards from my house. I then ranged a house at 478 yards and was able to make out the texture in the brick. I believe under the right atmospheric conditions (limited heat waves) I'll be able to see 30 cal bullet holes at 400 yards, but we will see. For the price I have been happy with my purchase so far. Now that I have the 50 mm, if I got another spotter I would skip the 65 and get an 80-88 mm.
I keep looking at the vortex razor 11-33x50 also and it doesn't seem like there are very many reviews out there. I have an inexpensive redfield rampage 20-60x60 and its decent but as I get older I want more quality stuff that I can afford now. I have looked at some higher end stuff in the store but I can't see much difference from mind than the higher end stuff. With that said I have been told you can't compare spotters that way you have to do it outside to get a good comparison. For me I think the little razor spotter would be a great back packer scope. Just haven't had a chance to look at one yet and I'd like to be able to take it outside to look but that can be difficult to do at times. Good luck hopefully you can give us an update if you get one.