Improved brewing technology increases our control over quality within any N-dimensional space of input variables.
The 9-bar standard for peak pressure during espresso extraction appears to have been established quite some time ago. How far can we bend that guideline?
An increase in pressure provides an increase in flow-rate, so if we extract at 11 bar, we should be able to grind finer than we do if we extract at 9 bar.
Have you tested many extractions > 9 bar?
Pressure / flow profiling can allow for a slower start. E.g.
2.6 bar 8 seconds
6 bar 4 seconds
11 bar 4 seconds
6 bar till finish