We love the new LED lights, they show up even the smallest hazard on the road and do a lot for safety, and are good for the environment, a win- win! 
  On straight roads a properly lit cyclist can be seen from a long way off, so the odd light out doesnt matter, so I dont report them. Junctions, where headlights dont face the ultimate direction on corners, are particularly hazardous in the dark. Amazingly, these are the points were most lights are out, especially roundabouts where often most of the lights dont work. I have no idea why this might be, do you know?