Review of the fantastically complicated 9Barista stovetop espresso machine

Coffee YouTuber James Hoffman reviewed the 9Barista stovetop espresso machine. Here's a half-section illustration from the  9Barista website so you can see what's going on. It has two boilers, a heat sink, a coiled heat exchanger, and a spring-loaded valve:   It's available from the 9Barista espresso website for $385.