While the TMO version does in fact have all the AT&T LTE bands (your AT&T SIM will work), the hardware itself does not contain all the same bands as the AT&T version. Our TMO version supports: LTE Band 02; LTE Band 04; LTE Band 17 and the AT&T version supports LTE Band 02; LTE Band 04; LTE Band 05; LTE Band 07; LTE Band 17
Eric, get the TMO Moto Maker version as it will work on AT&T bands. It is SIM unlocked so it will work with any nano SIM you put in it. However, the AT&T version is SIM locked so you will be limited bringing it to an MVNO.