I had the 1-4 Viper PST. It was super nice over all. I realize its not gonna get you out to 600 yards BUT I can tell you about the scope in general.
Robust and durable
Very nice, crisp, clear glass
Kinda shitty zoom adjustments, throw lever would be nice (apparently you can order these separate)
No end caps to protect the glass, the ones vortex sells separately BLOOOOOOW
I loved the reticle on mine, it was a 1 moa or less dot with four like quarter circles around it, kinda like an Eotech. It also had additional lines to account for drop at more distances.
I also really liked that it lit up and the on dial was like on off on off every click, so you could just put it up about where you like it brightness wise, and click once in either direction to turn it off and back on.
Overall I really did like it and hate that I traded it...