Should I choose a vibration pump or a rotary pump?
Italian coffee machines come with a choice of either vibration or rotary pumps. Traditionally rotary pumps had the advantage of being quieter but some of the new coffee machines have closed the noise gap with some clever engineering to eliminate the "vibe rattle."
Coffee machines with vibration pumps have a slight advantage when it comes to espresso extraction due to a more gentle pressure ramp up. This means that espresso extraction starts with a gentle wetting of the coffee puck, followed by slow pressure ramping up to full extraction pressure. Rotary pumps ramp up to full pressure quickly which means that the coffee puck is hit harder and faster, increasing the risk of channeling and uneven extraction.
Of course, if you want to plumb in your coffee machine your will need to choose a machine with a rotary pump.