Re: Viper PST or Nightforce NXS
You first need to decide if you need/want a FFP or SFP scope. Now, it was mentioned that you should get a FFP scope if you are to be ranging with your reticle. Ranging with your reticle is not a problem with a SFP scope and shouldn't be a reason for deciding on one over the other. If you want to make shot corrections using the reticle, hold-overs using the reticle, engage movers, etc., then the FFP is desired.
If you are going to be punching holes in paper, a SFP scope will suffice and will probably be preferred. With tha said, I have no experience with the PST and have had mixed results with NF scopes. Of the two, I would get the NXS if I could live with SFP and the PST if I needed FFP. Personally, I would choose a third option, but no other choice was given.
Also, as far as 10x or 16x being "enough" power for shooting out to 1K - yes, it is "enough" if that is what you have. A Smart car will also probably be "enough" car to drive across the country, but only a moron would actually do it. Small targets at distance make more magnification attractive.