I have a TMO hotspot with band 12. I have to tell you that as far as coverage goes, my Cricket phone on AT&T gets much better coverage. Generally if I am close enough to a larger city to get good TMO service, then I also have Sprint. It's not always the case, sometime one or the other has service. Verizon almost always has service and I have only seen a few spots out in the boonies that Cricket did not.
So look real hard at where you will be and the coverage they offer before switching. Quartzsite as a example was barren for TMO but Sprint had at least 3G. Cricket was fine but Verizon overloaded one night when the big tent opened.