My Mini is now 23 years old and this is only the second time I've replaced the burrs. As it's used in a residential setting perhaps that not too scandalous, but I did leave it later than I should have: I could see excessive wear under magnification and added fines in my espresso. I chose the genuine Mazzer burrs because the extra cost over non-OEM versions is negligible over the period of use. Though no longer fashionable, the Mini is a solid performer and I'm happy to breathe new life into it with a new burr set, rather than opt for an expensive replacement of lesser heritage.