After reading this thread, i basically figured out (correct me if i'm wrong)
Model A1865: Global model, supports every country around the globe.
Model A1901(?): basically focused on USA + Europe ?
Therefore the A1865 model is the "superior" model?
Correct in spirit, but not in fact.
Both the A1865 and A1901 support every country around the globe.
The A1901
only has a GSM radio in it so it can
only connect to GSM towers and receive GSM signals.
The A1865 has
both a GSM radio in it
and a CDMA radio in it so it can
connect to both GSM and CDMA towers and receive both GSM and CDMA signals.
GSM is far more popular worldwide than CDMA. There is a ton of GSM connectivity in every country with brilliant LTE connectivity. 95% of world travelers will have no issues with the A1901 and awesome LTE speeds on GSM networks in Europe, Asia, Middle East, everywhere, it's nothing you really need to worry about. Unless...
....you wind up in some small villages or provinces in places like China, South America, and Africa. GSM isn't everywhere. In some locations only CDMA exists. And, in even more cases, even though both GSM and CDMA co-exist, GSM is only 3G where CDMA is LTE. It's in that 5% scenario that having an A1865 dual-band iPhone X is beneficial as you have both GSM and CDMA radios for connectivity.
Bottom line is that 95% of the iPhone X buying public doesn't have to worry about having an A1865, doesn't need to stress about anything in this thread. It's really for frequent world travelers who wind up in some obscure places. I'm one of them. I am in small towns looking at factories in China, Europe, and South America. For me, CDMA is a must-have.