I backflush a Synesso Cyncra every day, at work. With a blind the pressure gauge reads at 10.5; however, during a pull it reads at 8.5.

Logically it's a very simple premise: it's the difference between applying pressure to a solid object versus a porous object. The coffee provides a finite resistance. The blind provides an infinite resistance.

double_pedro wrote:If so, isn't the point of all of this simply that the blind PF pressure measurement establishes is the maxuimum brew pressure but can't say anything further about the actual brew pressure as this depends on the grind, tamp, dose?

I think that was the point the OP was making.

Are there any machines with the OPV adjustment on the control panel? That would enable another level of control over the brew process. While were at it how about a flow meter readout for brew water in something like ml/s. I don't know if the standard flow meter in auto machines can be connected to a readout or produce a reliable signal at so low a flow but I know from instrumentation world that it can be done. I guess the maximum modern machine will have all parameters on a front panel readout and all user adjustable.
KDM

For what I see, a flow meter readout or (even worse) an OPV adjustment on the control panel would not be helpful in anyway. It would detract you from one simple rule: While producing, the only parameter is the grind.

An auto dosing espresso machine is a huge step to achieve stability in brew strength. Set it and forget it.
The same goes for the OPV. Thanks to the designers that they usually hide it under the hood.