I say double blind testing is in order. There was a recent article from a coffee tradeshow that seemed to indicate the conical was the crowd favorite.

Honestly, without a double blind test, we're all subject to our biases and influences. I would venture that in double blind testing, even experts would not be able to reliably identify either burr type by simply tasting the resulting beverage.

There have been any number of trendy notions on the 'net over the last decade that I've been seriously making espresso, most have come and gone and few have really stood the test of time.

I have certainly been able to prepare very light and "scandanavian" roasts on a number of occasions with no difficulty at all with the Monolith Conical and the LMLM.

We spend way more time dinking around over equipment than we do coffee - curiously being that coffee is the most important part of the whole process.

If anyone can point at a bean that can only be ground and served from a flat grinder and not a conical grinder, please point me at it.

How you can say there is no difference in taste that human can feel, if you pull shots with the same coffee with a big conical (83 mm) you usually get 19-21 % EY and with a big flat suited for light roasts you can get 24-26% EY?

These phrases you wrote are just to implement in your mind and some others that you don't need to upgrade, or another mill because there is no difference between them. Or maybe you don't see/taste any difference and then there is a problem with you not with the equipment.

There is a huge difference but you have to extract with both in the way that maximizes the extraction for each grinder. If you do 30 sec shots for both then you are doing a big mistake. Now I see people are stuck into numbers (1:2 ratio, 25-35 sec, 18 g dose) but coffee is not about that, coffee is not about numbers. The numbers were made for an easier way for beginners to understand from where to start.

Each coffee and piece of equipment has to be exploited different to get the most out of it. This is the difference between coffee enthusiasts that progress and people who just enjoy a cup of coffee.

I did some testing between 83mm conical, 75mm Mythos and EG-1 and will never go back to conical burrs for the light roasts I'm using. It's a pretty big difference once you get it right and the flat burrs win hands down, no doubt about that. Those flat burrs are able to give a much higher EY than what's possible with conical burrs and that makes all the difference.

Maybe you didn't have light roasts that where developed properly. I usually buy my beans from Tim Wendelboe, Coffee Collective, Friedhats and La Cabra.

On topic again: You could add the Ditting 804 LAB SWEET to the list of very good grinders for light roasts and capable of espresso.