The LTE bands of T-Mobile NL are: band 3 and 7
The UMTS frequencies of T-Mobile NL are: 900/1800/2100.
And according to the Wikipedia page of the Moto X, the AT&T variant(XT1058) supports LTE band 7 and UMTS frequency 900/2100.
So will LTE and UMTS work on my carrier?
Is the AT&T sim unlockable/bootloader unlockable/rootable/customromable?
And am I better of buying the Dev Unlocked GSM variant?