Hi, for that 1K range I feel that the Sightron is an excellent choice. I have a 6-24 sIII SS right now and did have the Vortex before that. I feel that the glass and clarity was very close, with the edge going to the Sightron and the bells and whistles going to the Vortex. I traded the Vortex 4-16 PST back to the dealer for a 5-20 Razor HD, and it is definitely a step up from the Sightron and PST but not a huge step though, although twice the price.
I have set the Razor side by side with my Sightron and have done several comparisons with other shooters who have done lots of long distance shooting with various scopes, and it is unanimous that the Vortex Razor is clearer, etc.....but every person who looks thru the Sightron is surprised at how nice it is and how close it is in comparison for 1/2 the price. If absolute clarity is key, I'd go with the Sightron, but I love the Vortex stuff and their no hassle warranty and also that I had my PST for 2 months and the dealer took it back on trade for my new Razor....hard to beat that kind of service!
A good friend who is a long time very knowledgable precision shooter has been a die hard Bushnell guy for many years and has a couple of the Bushnell 6500's, is actually going to purchase a PST for his next rig after looking thru the 4-16 PST at the store this week. for what thats worth. Don't think you will go wrong with either of those scopes you are considering.