Coffee

I have a df64 and a 1zpresso J Max, which IIRC is 48mm conical. The product tastes pretty similar in an aeropress, although I would say df64 is slightly better (could be due to many things, like conical v.s. flat, geometry etc.), but not $200 better.

The speed difference, even considering hand grinding is negligible unless you are making coffee for more than 4 people.

In general I find the diminishing return might hit you real hard if you decide to upgrade; but it is a hobby anyway: if it makes you happy then it makes you happy; who am I to judge :)

The only significant difference flavor-wise I'm aware of from burr size is that a larger burr has more mass, and is more resistant to heating up from friction during use, with that accompanying expansion changing the grind characteristics. Tbh though, I think you need to be going either high volume at a commercial scale, or be trying to perfectly nail some ultra-precise extraction recipe for an award-winning cup of coffee for the thermal expansion to become relevant.

Maybe not burr size exactly but I've had an experience with grind size on my fellow ode being the difference between extremely bitter almost burnt taste and good taste on the same beans for pour over.

At home I currently used a DF83 with the SSP HU Burrs for espresso, a Timemore 78 for pour over. For travel I have a 1Zpresso J-Ultra for espresso and a ZP6 for pour over. In the past I have owned a Niche Zero, Eureka Mignon Brew Pro, Quamar M80 E.

Burr size ignoring the changes it makes to burr geometry has little baring on what you get out of the cup, espresso or pour over. The burrs themselves? Potentially massive differences, but their are caveats.

Water, then beans are the two most important ingredients to your coffee. Sure, a great grinder will get more out of bad beans than a bad grinder, but it cannot cover up that they were bad beans to begin with, they cant invent flavor for you, only reveal it. And no amount of great beans and grinder will fix nasty tasting water.

Also if you only really drink dark roast and not medium to light roast, coupled with a preference for an espresso with a ton of body, then ultra low fine production grinder/burr sets aren't going to be giving you what you want and will make your espresso feel too much like thin tea.

Having said all that, the particle distribution of a grinders output is something thats been measured many times. Its quantifiable that a better quality grinder, something with a proper pre breaker like a Zernos auger, and just all round high quality will produce a lower distribution of grind sizes. It is going to provide a more consistent cup of espresso than my DF83, but then its £2.5k for the same setup, when I swapped my Niche for the DF83 and the DF83 was light years better than the Niche for clarity.

comparisons between burr sizes will mostly be a bit apples to oranges, since you dont have same design same manufacturer same burr tooth geometry with the only difference being burr size. but yeah, seems to me bigger burrs all else held equal should grind faster and quieter. the levercraft ultra grinder with its ~100mm burrs is the quietest grinder ive encountered

The change from nice hand grinders (Knock Feld 2 and Helor 101) and the Fellow Opus to the Fellow Ode 2 was drastic. The Ode 2 produces very few fines which greatly increases clarity and the speed in draw down time for the water through the grounds. I am doing pour over not espresso.

The hand grinders and the Opus all produce far more fines than the Ode 2.