I have experienced lower flow rates, I have a DE1Pro too and pull shots typically at a 0.5 ml/s flow rate into the cup and at various brew pressures.
Also, with my Izzo (plumbed in) I can do line-level PI, currently set to 2 bar (in line pressure regulator) which gives me a flow rate 6.4 ml/s without the pump being engaged. I can also pause and soak (without engaging the three way valve) and I could set the brew pressure to 4 bar and do the extraction. But I will have to completely change my grind level (much much coarser) and possibly my dose and at that low pressure I can foresee decreased crema and body and mouthfeel because of limited emulsification of oils due to the low pressure. If a certain minimum high brew pressure was not necessary to achieve this emulsification of oils into a colloidal dispersion then what is the point of the commercial espresso machine with it's ability to generate intense pressure?
But what I want to do is a declining pressure profile starting at 9 bar and declining as I go towards 6 or 4 bar depending on how the extraction is progressing. Everything else I can already do with my E61 and obviously with my DE1Pro.
Anyhow, I think it is possible to do what I want if I set up the valve as explained above (fully open) and starting the shot with the handle all the way around to the right.
I had 2 customers who returned the DE1 for the Bianca.
Interesting points. I have not changed my grind level coarser (unless I change beans or blends), nor changed my dose. These remain the same. Some low pressure profile shots do have less crema, but the flavor profile goes through the roof. The one for the roaster today was all crema. Some of this will depend upon the coffee.
Anyways, off I go to SCA Boston. The Bianca will be in action at the Bravo Beverages booth #152.