Our old Heart unit (25 years old is probably still working on the new owner's boat). I understand they're still using it. When we replaced our Heart with a MasterVolt unit, I gave the Heart, the 2000R, and the smart regulator to someone. They're still using it without issue. Maybe they've been lucky. Of course, when it goes, the "smart" regulator that it connects to isn't made anymore. They're all on their last legs...
But what would you do to control the Heart of Xantrex to replace the Link 20?