Cuprajake @DavecUK will know, years ago didnt the get a bunch of coffee guys together to blind test and they couldnt tell the difference between flat/conical.
Proper testing has been done and yes in general it can be inconclusive…like everything though….it depends
I had a coffee where as an Americano made from a conical from an Espresso machine it was great…but then I tried it on a big flat as a pourover using an open cone and number2 filter …it blew me away. Grabbed the big flat and dialed in for espresso….was good, but not as good as the pourover.
The same for espressos and americanos…some made with a conical are better than a flat and some made with a flat are better than a conical….this was down to the particular coffee (not roast level, because I have had this with light and dark coffees). The truth of it is, it depends on the coffee and then the prep method that complements it….isn’t just the same cookie cutter setup..
The problem comes with discovering what’s right for a particular coffee, flat, conical, brew temp, pressure…I’ve often found a healthy slice of luck is involved, as there’s so many variables. The ideal really is to have a flat and a conical. With flats one thing is very important. Over my years of testing I have found espresso specific or filter specific burrs are optimal, depending on the type of coffee you are making. People may disagree but for a big flat, there might be a do it all burr, but it won’t be as good as the specific burrs for the job at hand.
