It's harder to compare Crinacle vs Oratory because they have different measuring processes, albeit comparable rigs. If Crinacle saw variation using his own rig, then that is something to consider, providing he uses a consistent measurement method, which I suspect he does. In my experience Sennheiser are very hot on unit to unit variation, so you theoretically should have a good experience re using Oratory's measurement for instance. And I just looked at HD800s on Crinacle's website, he measured 3 units, they're all close together, so should be fine to rely on the Oratory EQ for instance, or Oratory measurement if you wish to EQ to another target.