Maybe it's a good thing Xiaomi doesn't yet offer smartphones tuned for North American LTE networks; the company has a bit of a problem respecting software licenses.
If you're not familiar with the particulars of free software this can get confusing real quick, so let me know if I lose you. Basically, if you thought that all those wonderful custom ROMs available on XDA were massive reverse-engineered hacks you'd be correct in some cases, not so correct in most. Android, if you didn't know, runs on the Linux kernel, and the Linux kernel is governed by a very specific software license called the GPL, or GNU Public License. What's GNU? GNU's Not UNIX
—recursive acronym, long story, not really relevant to what we're discussing here...
What is very relevant is the terms of the GPL, which allow for any and all modifications to the Linux kernel (for example) provided that those changes are made public
for the benefit of all users. Thus, there's a reason why Android modders tend to gravitate towards Nexus devices and, more recently, the OnePlus One
: Google and OnePlus (actually Cyanogen, Inc.) release the source code
for their hardware, which ROM makers use to build their firmware, which modders then download and flash. Everybody wins.