I dropped off my MS3 last week at Morgan Brussel.
They confirm to me that the belt transmission will always make a lot of noise, that they have a special grease which helps reduce the noise, but that it is temporary...

that's why they recommend chain transmission, it's a free option when you order a new MS3, it pays when you have a belt MS3 that you want to convert to a chain...

But they confirm that the difference is enormous!

However you have to pay...again....
