Update: I have found that I don't wear it all the time. If he's fairly settled when feeding then the necklace just distracts him and he ends up tugging quite hard. But if he's already distracted then it's ace because it means I don't constantly have to turn my face to stop pinching, poking and pulling.
So, by default I don't wear it all the time, but do keep it nearby for the more fidgety feeds