Thermal stability is arguably one of the most important aspects of espresso machine. If the water in the espresso machine boiler is sitting at 95°C, by the time this hot water reaches the group head it will lose some of the temperature. Lose 2°C and you're good. Lose 5°C and you still might be good but already at the edge of getting the crap out of the machine. Lose more than that and you're not gonna want to drink it.
Traditional E61 espresso machines whose water boiler is at ΔT cm's away from the group head, solve the problem of temperature surf with heavy duty pipes, boilers, isolation and materials to keep the temperature loss at the minimum.
More modern espresso machines place the water boiler just above the group head so they're basically solving the problem other way around: keeping the ΔT at minimum so giving no or minimum space for temperature loss.
As for this design, I am not sure how does it solve this problem.
Traditional E61 espresso machines whose water boiler is at ΔT cm's away from the group head, solve the problem of temperature surf with heavy duty pipes, boilers, isolation and materials to keep the temperature loss at the minimum.
More modern espresso machines place the water boiler just above the group head so they're basically solving the problem other way around: keeping the ΔT at minimum so giving no or minimum space for temperature loss.
As for this design, I am not sure how does it solve this problem.