Except you actually heard real omega drivers in that unit.Pretty much mirrors my experience with the two. Generally similar presentations, with the x9000 being a bit more technically proficient while the Omega is smoother, with a bit more natural tone/smoothness. I would only add that the Omega was very impressive technically, just that the x9000 pushes that a bit further. If I could only choose one or the other, I think I would go with the Omega because of that balance, but it would be tough. The only thing for me with the Omega was that it felt just a bit less engaging (i.e. more laid back as you say) than the x9000 or HE90/R10 I auditioned it with. But smoothness/laid back sound is kind of an inherent tradeoff with more energy, detail and potential harshness for some people's ears.
So fully agree it just comes down to preference and what a user is looking for.
edit - and also agree with your thoughts exactly on the ES-1a as well.
Further goes to show that the sound signature of vintage gear is preferred by many.