I've just put one on my main comp gun, really really good glass and build quality. The hft masters event at Greyhound a couple of weeks back was my first competition with it and was rather nice to use & had a good round.
I think sightron may have made some improvements in the turrets as there is no way you could move them accidentally. Good positive clicks, you also have the option of adding an o ring in an existing groove between the outer turret housing and inside of the turret cap - I did this as a precaution which adds a little more resistance, but also stops any water / dust ingress to the turret mechanism.
Re potential parallax error, I use an enhancer which healps get a consistent head position. Some like them, some dont, its a personal choice thing.