devils advocate - its the weight of brass and thermal inertia that carries it during the brewing process, can the boiler heating/electronics really contribute during those 20s or so ?
I've never heard if there is much variation in PID type algorithms.
It's less about the thermal inertia of the components and group head and more about the temperature of the water in the brew pipe.
In a Heat Exchange machine the boiler heats the steam water to about 127C, the brew water passes through this boiler in a coper pipe, if its sat there too long it will get to 127C when you really want it at 90C.
This is why you typically need to do a cooling flush on a heat exchanger to purge that 127C water in the brew pipe, wait for a bit for the brew water to hit 90 and pour.
I'm not sure what the MaraX is doing to keep the temperature in the brew pipe down, but it seems to work according to all the tests i've seen...