I have not. I guess the fact that putting 60g in all at once produced fractionaly less fines argues that slow feeding might have diminishing returns.

Agree. In general you have more room for finer grinding with lighter roasts, but I think that’s an over simplification. Personally I just tweak the grind size and / or try a different brewing method if I’m chasing the right taste for a particular bean. Could consider adding this as an option to try too, but usually I run out of beans before I run out of ideas for things to tweak on each brew already. With a few different beans I tried (all South American or Ethiopian) , I didn’t get any real wow results with this though. There are some nice apps for wines where you can take a photo of the bottle and then pull up price checks, tasting notes, and reviews. I’ve always thought this would be cool to do with coffees with the added benefit of sharing bean specific brewing notes.