Can't say I've had any problems yet with my K3's - but they are many years old. There is nothing special about the K3, I just like them because it is easy to free dose - which is the way I always make my coffees - no measurements/weighing......just eyesight and this works perfectly for me. Perhaps the reason I like the K3 is because they are slow at grinding, which makes it easy to pulse on/off to get just the right level of coffee I need for the dose. I do have a lot of problems with my A8 and a couple of K10's occasionally with motor stalling - but I believe there is a simple workaround for these on Compak grinders (including the K10's) by changing the wiring on the capacitors - a job for one day when I have some time.