The selection knob on the mini has firm step positions. the steps on the MK3 are a lot softer, and it happens once and a while that by pressing the knob to make a selection it shift one step and the wrong file gets selected for printing. this is mainly because te surface you handle with your finger is big an therefore mor prone to movement during pressing. by making the top surface a lot smaller, the chance of turning the knob accidentally while pressing is almost nihil.