and nunas suggest i further reduce the pressure to 0,8BAR, well, I might try that, and so what kind of recovery time I should expect with that kind of pressure?
I'm not sure I can answer this question properly, as I've never tried 0.8 bar. But, I think with the nice big boiler in your machine, recovery time at any reasonable pressure would be very quick. I run my machine at about 0.9 bar because the Magister needs a long cooling flush. Even at 0.9, to get the temperature down to around 85 to 90 in the PF (about 3 degrees higher on the EricS thermometer), which is the range I like for most of my coffees, the flush takes about 20-seconds. Unlike you, I do a lot of steaming, or I'd also drop the pressure. Of course, every brand/model of HX is different in this regard. Once I flush to get the temperature right, it will drop a bit more on the first pull, but after that, subsequent pulls are quite stable. That is, I don't have to wait any appreciable time for any recovery...just the amount of time to grind and tamp a new PF full. Usually, I pull only two or three doppios in a row; so I can't say how stable it would be if I pulled more. I'm guessing that it (and yours) will be very stable. We heat such low volumes for our shots that the reheating process through a large boiler full of >100-degree water has to be quick. Also, bear in mind that no water exits the boiler, as the brew water comes from the reservoir, through the HX to the group head. A typical 1300 Watt element, if asked to boil a couple of ounces of water would do that nearly instantly. But, this is all conjecture. Please let us know how it goes at 0.8 bar