Does AT&T not need the the additional LTE bands that are in the AT&T version and not in the Pure edition? This is from Moto's site:
Moto X - Pure Edition (GSM Unlocked with T-Mobile SIM - XT1095):
GSM/GPRS/EDGE (850, 900, 1800, 1900 MHz)
UMTS/HSPA+ (850, 900, 1700 (AWS), 1900, 2100 MHz)
4G LTE...