What is your experience with leakage from the 840 pads? this is my only concern by now as the sound was pretty good after messing with the cloth. for me leakage was to much (I could hear it from 5 meters in a silent room and tell which song it is at medium volume) but this could be a problem with my pads only as I maybe did a little too much to them while experimenting.
we need to figure out a way to 'seal' the fabric of the 840 pads at least on the inside. i bet this puts the FR back to being competitive with the OEM pads while adding the much higher comfort of the 840.