Hello. I am planning to purchase retina ipad mini LTE. Thing is... in a given year, I will probably spend about 1/3 of the time in Korea and 1/4 in Canada... rest in the US. I want to be able to simply swap out the nano sim whenever I am in Korea or Canada to use lte service. My understanding is that this is not a problem no matter which service I originally get since all the machines are the same. Am I correct in thinking so? Is there anything I should know or consider before making a choice? If there are differences, which service is best suited for my needs? I was considering T-mobile since they have very good international data roaming plan for when I am traveling and need to roam. Any help is much appreciated. Thanks in advance.