I am reading from posts that the Verizon version is compatible with both GSM and CDMA, and so it works with both T-Mobile and AT&T giving you the most carrier flexibility. Is there any advantage to getting the T-Mobile or AT&T unlocked iPhone X over Verizon then? Is there higher battery life in the non-Verizon versions because you don't have to support CDMA? or is there some optimization for the T-Mobile and AT&T networks when you use their iPhone versions? Or is it that Apple has the T-Mobile and AT&T versions just to cut costs for 'cheaper phone manufacturing/higher profit margins for Apple'? AT&T version of the iPhone sold out first at the Apple store I went to.