I have one and love it. I was the one you may have seen talking about the screws backing out.
Well, I recently fixed the problem. Two of the three steel pins that hold the unit together do not have much to grip on to. So, they often spin around and it is hard to tighten them down because the back part is just spinning.
So, what I did was put a light coat of Loc-tite on the outside of the steel pins themselves. This gives them good grip so they don't spin. After letting it dry, I was able to really tighten my screws down good and it has not lost zero at all in the past 3-4 weeks, even with holstering and unholstering once or twice a day.