Since I was the primary MIUI maintainer for Sprint Evo 3D and M7 (and have since moved to VZW M8), let me address this somewhat old question.
I will be doing a port to VZW just as soon as Xiaomi releases an international M8 ROM. I've been watching their release news somewhat regularly, but haven't seen anything just yet. In fact, I stumbled across this thread searching for possible other releases. Either way, I've got lots of practice porting to VZW M8 from Intl. version via my GPE port, so it's literally just a matter of waiting on Xiaomi.
As far as the comment about MIUI having a large number of bugs...not sure where you're getting your info from, but that's dead wrong. IMHO, MIUI is by far the best ROM I've every used.