It's not just consistency. It's grind size distribution. The cost of a high end burr grinder is crazy and I don't understand what's going on but you can do simple comparative tests.
I have a 2 different burr sets for my grinder with different cutter geometries and the mechanical properties of the grinds and the puck are different. Never mind the taste. The way the water pours through the puck and what's happening inside the basket as you pull the shot is different. You can easily tell by the amount of channeling I get and the integrity of the puck after the shot.
The espresso also tastes different BTW.
I've also done blind taste testing with my grinder pitted against 3 other grinders. Having only tasted the coffee from 1 of these, I matched the coffee to the grinders only based on the theoretical properties of the burr sets.
Some Taiwanese folks crowdsourced a bunch of manual grinders in this forum thread to measure and compare grind size distribution [1].
It's usually my go-to thread whenever someone asks me for grinder recommendations, and care mostly about the end result.
[1] (link in Chinese) https://www.mobile01.com/topicdetail.php?f=640&t=5747652
I'm a simple soul, if I can't measure it really easily I don't worry about it.
It's not like any two beans are the same and I'm tamping them by hand anyway.
Worrying about the shape of the blades in the grinder is like worrying about the type of power cable on your hifi amp. It's too much connoisseurship for me personally but more power to you if that's your bag.
Spread a small amount of ground coffee out on a piece of paper. Observe the varying sizes and shapes within the grounds. Better grinders produce more even grinds which produce more even extraction during brewing.
It’s an exceedingly simple concept. As an extreme example try and brew an espresso using a simple blade style ‘grinder’. It will be impossible. The refinement of a good grinder is simply optimizing along this axis.
You like what you like.
I'm just saying that your dismissal of the effects of your grinder are very wrong. And the differences are easy see and measure.
I think there's a small typo there, 9 bar would be more regular for espresso.
I agree otherwise. I treat moka or aeropress coffee as its own thing; it's not espresso and that's OK.
I see a lot of people talk about "grind" as important.
Really it's just a way of varying pressure and to keep it roughly in that 9 bar zone.
The only magic in a good bur grinder is its consistency. You can look at what you're getting out and bump the pressure up or down slightly compared to your last shot.
So as the beans dry out with age, you can increase the extraction so you don't get a flat, sour shot with no crema. If you put in a new bag of beans you can make the grind courser so that pressure is reduced and you` don't over extract.
I love a morning espresso but I'm less keen on all the connoisseurship around it.