I have had a Mastervolt Combi, shunts, and remote monitor. I've been very happy with the system and the ability to control, and monitor functions. They have been owned by the same company the owns Marinco for some time. They also are under common ownership with Blue Seas, Ancor, etc.
https://www.mastervolt.com/about-mastervolt/
Their Lithium Ion Battery systems are extremely expensive. It is high tech stuff. I couldn't bring myself to even consider them at that price. (I just bought 2-300 amp hour Relions to replace my Lifeline AGM's after years of experiencing declining durability of their batteries.
Mastervolt's Lithium Ion batteries and systems are used on a number of vessels, including the Volvo around the world racers. Those guys could use ANYONE's systems without regard to cost.
Having said that, I don't know the "value proposition" of the Xantrex or Magnum off-the-shelf makes it worth it for many boaters.
I'd buy the Mastervolt again.