The issue might be that the there was a lot of variance in the panel positioning on the headsets due to the positioning of the panels being a manual process.
I have had two 5k+ headsets due to cracks. My first was fairly good at default settings just a little eye fatigue after use. My second had horrible double vision briefly when putting on and taking off the headset. I fixed it with +2 vertical offset in one eye and now it is more comfortable than the first.
PimaxUSA has confirmed that there is now an automatic process in place to detect alignment issues on newer headsets. He also mentioned that before there was more variance between the headsets.