Hi leveraction and welcome to CS.
I dont own one myself.... but was seriously considering the purchase - until I did some internet browsing!
The following is a recollection of the "facts" I found.... so I wont guarantee they are 100%
The machine uses a pressurestat rather than a thermostat.... the boiler is always under pressure so it can texture milk instantly.... and force the water into the PF when you raise the lever.
As the boiler is under pressure the water it contains if far too hot to brew coffee.... it will burn it - giving a *bitter taste.
The machine relies on the group to be cooler than the water.... and hence when you raise the lever... and pressure forces the water into the group from the boiler.... it is cooled to *the correct temperature for extraction.
From memory you want to extract as soon as the light goes off.... and that way the water will be cooled correctly....
Dont extract more that two shots without letting the machine cool down..... dont allow the normal 30 - 45 minutes heat up from cold (wait just long enough for the light to go off).... and dont allow it to remain on between shots..... the PF will overheat..... bitter coffee!
As I said, the above is from memory - do a Google search and you will find all this info first hand.
I decided - although I loved the look of the machine - this all sounded too hard!