I'll just echo the other posts here. I tried bringing my MotoMaker X over to T-Mob and it was gigantic headache since I live in an unfarmed area (and an area with craptastic HSPA speeds, but that's another story for another day!). If you're looking to use a Moto X on T-Mob, just save yourself the trouble and either get the GSM Dev Edition, or the T-Mobile edition. Not as "pretty" but pretty don't mean diddly if it don't work!
Current Devices: Moto X & BN Nook HD+