hedonist222 - it does look like it! The thing with HX machines is simple: the boiler temperature is at 125C or thereabouts. There’s a pipe which goes through the boiler. That’s the HX. Water goes from the tank to the group, through the HX. The water inside the HX will, eventually, get to the same temperature of the boiler.
Now… the water inside the HX, circulates to the group and back - that’s the thermosyphon and that’s what keeps your group hot. But… as much as the group will act as a cooling sink, eventually the water will overheat. And that’s when you need a cooling flush.
If you have a machine which has a flow restrictor of the right size, and the water circulates in a way that it keeps the temperature stable for your needs… happy days. However, this might also mean the recovery time in between shots is also longer.
In comparison, I used to own a Rocket Cellini HX. Pressure was at 0.9 - 1.1 bar (low/high), and the would always overheat. Maybe Rocket changed things since.
PS: good to see you here. 😉👍