ST30B Seems most have both burrs so assume you wld just use the filter burrs
I only have the espresso burrs, and a I don’t drink filter coffee. The filters burrs on the Duo are ideal, exclusive for filter burrs. If you just want to make the occasional filter, the espresso burrs will do a job just fine.
ST30B I doubt I’d want to try different espresso burrs tbh if the mazzers are that good
Taste and “being good” are very subjective. They are traditional and well made. More importantly, the grinder was designed and tuned with that burr set, so changing to something else 10x more expensive might not be optimal anyway, but no different to fitting aftermarket burrs to any other grinder.
I’m drinking a medium dark Brazilian coffee at the moment. To my taste, for that coffee, the Niche Zero wins. I’m not saying the Duo is better than the Zero or vice-versa. I’m just saying they produce different flavour profiles. The same could be said for making filter with the espresso vs the filter burrs. And, unless you you have both… you’ll never know the difference. 😉
Now, if that’s your “end game grinder”, and you enjoy filter coffee and drink it frequently, it would be silly not to buy both burr sets.