Sometimes I wonder, how many ppl truely tasted great espresso. How could any of these coffeegeeks/home-baristas make great shots at home if they never experience an "optimized" pull?
Each coffee (blend or single origin) has couple optimized zone, and need to be extracted in a case-by-case manner. What I found with many home users is that they tend to be locked into a single approach. Many do not understand why some coffee tasted fantastic while other are utterly crap even if they follow their routine. They either dismissed the "difficult" coffee or proceed to blame it on the machine.
I am very fortunate to have a great group of open-minded friends who are not afraid of experiementing and challenge the convetion. For all the home users out there... please never be satisfied with what you have and seek out those who can push you further. There are still much to be discovered...