My rainbow Love was purchased in October 2015 and screwed on by the SA. I was wary of the screws becoming loose after reading horror stories on the forums, so I checked them obsessively at the start and even took photos of the exact positions of the screws. Since then I've never taken the bracelet off or touched the screws, and they haven't budged. I'm currently wearing my Love with a Fitbit and have previously worn it with a watch/another bangle, therefore it does get knocked against other things, but fortunately this hasn't loosened up the screws at all.
I do remember the SA taking her time to make sure that both sides were lined up, and she tightened each side a little at a time as opposed to tightening one side completely followed by the other. Maybe the screws have to be tightened in a certain way on the new system?