It's a fair point. What made me a convert was drinking shots at RBC
in New York and Streets
here in Chicago; and then reviewing the Strega.
Neither cafe roasts their own, both buy espresso from a wide range of roasters. I've only been to RBC once. It is in a downtown business district, abandoned during weekends, and yet was quite full on the Saturday we went. Streets I've been to quite a few times, and it never has the same coffees on tap. Both routinely make unctuous shots from very light roasted coffees, drawing people who like straight shots.
Obviously, one cafe each in two very large cities does not make for a trend. But I know good espresso, and both these places have pushed out the envelope, not in some once a day shot, but for just about every shot they pull. Cafes that compete on espresso taste cannot afford to ignore a technology that makes obviously better shots.
I had a chance myself to play with a somewhat limited version of pressure profiling on the Strega, a pump-lever hybrid machine
. My experience with this machine is that it is extremely easy to reproduce this shot quality. The elaborate PIDed time/pressure profilers on the current crop of machines are unnecessary, perhaps even misleading and therefore counterproductive. I just wait for the coffee to start flowing, than drop the pressure very fast, so the flow stays slow and steady, 3 to 5 bars as far as I can guess. This "profile" is not rocket science; to automate it, all that is required is to detect the start of the flow, and drop the pressure then. The timing of this event is very unstable, so time/pressure profiles, no matter how elaborately done, will not deliver consistent performance.
The people at RBC and Streets profile by eyeballing the flow, just as I do on the Strega. This does lower their milk steaming productivity. But once the flow onset can be detected, eyeballing and manual control will be unnecessary.
Finally, on the Strega, I don't bother with any pressure gyrations when making cappas; manual profiling is for straight shots only. That would work in commercial situations as well.