Even NF aren't immune to having the odd scope go belly up, but the failure rate is among the lowest out there.
I've been VERY impressed with various models of the Viper PST, so it's no surprise to see another one working very well.
All my Leupolds have tracked and RTZ reasonably well, although not perfect, but they've all required me to compensate for actual click values that varied from the advertised values. I've had a couple go bad on me, as well. The only problem I've had with Vortex scopes are the odd fleck of dust on an internal lens. Mechanically and functionally they've been excellent for me.
