I have seen it said here and in other places that even if the Kosher Switch is actually assur l’chatchila it would still be a good idea to have it in order to avoid accidental chilul Shabbos.
My problem with that statement is that in order to prevent chilul Shabbos, the switch has to be in “Shabbos Mode” which means that you would have to put all the switches in your house into Shabbos Mode every week. Once you are doing that, you might as well just put one of those classic covers over the switches to prevent them being accessed at all like many frum people do nowadays. And even if lu yitzor you did go and put them all into Shabbos Mode before every Shabbos, you still only avoid the issur if the green light is on so if you are switching it “accidentally” than you aren’t checking for a green light.