S4 T-Mobile vs AT&T

[agunjal]

Quick opinion. I know the T-mobile S4 has a few extra bands for LTE but is virtually the same at the AT&T. AT&T is willing to unlock it and I travel to Asia and Europe twice a year. Will I notice any real difference between the two models? If I use T-Mobile prepaid with a AT&T Phone it appears it will work....any opinions?