Very well said, guju...
Guju is right...
Once all I-485s are in the queue, it does not matter where you are from. The only thing I can think of is that if, God forbid, there should be any backlog, it'll reflect on the Visa Bulletin issued by the Department of State. I understand from few years back that my fellow I-485ers from India, Mexico, and the Philippines were subject to Priority Date cutoff; however, this is no longer the case for all EB cases are current.
I truly hope that NSC Adjudications Officers would look at each and every case, based on its merit rather than one's nationality. But then again, as guju has so eloquently put it, we will never know what goes through in those officers mind...
Japanese