tl;dr
It reduces the noise. Not even close to what's advertised, but reduces. It's too way sensitive, causing some unwanted triggerings even when we lower the sensitivity in the module.
Be aware about this before buying. It works, not exactly as advertised, and it has some trade-offs.
Long version:
I bought it because it was suppose to be quiet, and it's not THAT quiet.
Out of the box, without any modification, it has a high "metal to metal" sound. Once you add a piece of felt between the pedal and the trigger this high pitch sound is reduced, but not eliminated. There was still a clanking noise coming from the unit. This was happening because the area between the trigger and the plate was not flat enough. I sent Triggera a message asking about this clancking sound (which is not shown in their ad videos) and the suggestion was that I should brush the metal myself. I don't even have the tools to do it.
Here is the sound before applying the felt between the trigger and the trigger plate:
another pair of square felt between the trigger and the trigger plate and it helped to reduce the noise:
, as you can see, it still way louder than advertised. I'm really not sure if this specific unit is defective or not. Given the construction complexity and the amount of small "mods" I had to add in order to make it usable, I don't know if I recommend this or not, specially at this price point.