I had tbe M5, two sets and both broke. The motor went on my first set and the second set stopped pumping even if I was expressing fir over 20 mins, nothing would be happening so I brought a pair of Elvie pumps and love them. Wouldn't look back at all
I don’t have the M9 but I have the M5 and haven’t ever had issues with it. It can be a bit tricky to get the right placement but it drains me well!