I would describe the noise as greatly reduced. It seems that as long as the "ball" can still move you will be able to hear it, so it really depends on how strong a magnet you use. Currently my remote only makes the little rattle noise when I give it a shake, but if I listen for it I can still occasionally hear the rattle during normal use.

I refer to the unit as having a "little metal ball", but I haven’t actually seen it so it could be something else inside the motion sensor component. My assumption is that they have used a small stainless steel ball since it is obviously only mildly attracted to the magnet.