I have been using a Gen 2 PST on one of my rifles for the last year and I've had zero problems with it and I tend to like it. From what I've read and researched it seems the failure rate for these Gen 2's is much lower than the previous Gen 1's.
Vortex as a brand will always be heavily scrutinized. I would love to know the true failure rate of all brand scopes. I certainly understand that some will rate much higher than others. But some, at least in what I've researched have next to zero failure reported. Maybe that's partly due to the price tag and those not speaking up about the issue to justify it. I do believe any mechanical device can fail. Yes there are better designs that lend itself to be more reliable and repeatable but even with that nothing is perfect and everything is a tradeoff.