I have the Vortex Viper 4-16 SFP. Not exactly what you're looking at but the magnification is the same. It has worked well for me out to about 950 yards but I found that when I stretch much beyond 1000 I wish I had the extra power. If I were you I would go for the higher magnification, you can always turn it down if mirage become a problem. I am not sure if there is much, if any, difference in the glass between the Viper line and the PST line, that to me would make more of a difference than power range.