I have numerous Vortex Vipers in every flavor.
Typically, at high magnification, the eye box becomes touchy and at extreme elevation settings you can see a crescent moon in the ocular which is actually the scope tube inside. No biggie. If you want to get out real far, mount it on a 20 or 30 MOA rail. The illuminated reticle, I leave it off most of the time. If I turn it on, I always forget and kill the battery anyway.
Glass is good and I never had any dirt speck issues with any. I'd say the glass is as good as the Leupold Mark4 line (have one to compare with) but a slight bit less than a NF (borrowed a friends for comparison).
Vortex's all come with a real cheesey scope bra that you might as well landfill and get some Butler Creek flip caps and the Zero stop isn't really a positive stop but rather shim washers under the elevation turret that allows you to go past zero but not so far as to get a full turn. You can actually apply that feature to any scope with shim washers. Novel idea that can be applied universally.
No recoil issues here. I have one a 338, one on a 308, one on a 223 bolt gun and one on a shotgun. All fundtion perfectly.
The Vipers are made in the Philipenes and the lesser models in China somewhere, probably near onehunglow.....
In today's market, all in all, a good scope for a decent price. I suspect warranty returns are off to the landfill and ship out a new one.
I'd also consider a Huskemaw. Len sells them on this site. The lower priced Huskemaw is as good as the Viper plus Len can supply you with custom turrets and it's the same guarantee, which, is fast becoming an insdustry standard anyway.