Ayon vs. Mastersound vs. Vaic Tube SET

What is the relationship between Mastersound, Ayon, Vaic? Seems they've been using those names interchangeably. 

Also, I heard that Mastersound amps are notoriously unreliable because they create so much heat it causes the components to fail. Do they really have inherent design flaws? Also heard that their factory support is so poor which is why they're not well distributed in North America. I know there is only one dealer in Texas. 

If one is to acquire a mastersound amp, would there be any support in East cost NYC area? 
Does anyone know how the Evolution 845/ PF100 / Compact 845 from circa 2010-2013 different from Most recent model? Have they improved reliability ? 

Which Tube amps rival Mastersound ?