It is unsafe to allow cats out on narrow ledges or open roofs several floors above the street. Many animals are injured and killed every year through lunging at a bird or butterfly and missing their footing. It is not true that a cat will 'always land on its feet'. Apart from the callousness of picking him up from a warm, comfortable snooze on the hearth rug and putting him out in the cold, there are the risks of road accidents and stealing. Most road accidents to cats take place during the hours of darkness.
Cat stealing, unfortunately, does go on and mostly at night.
Keep your cat safely in at night and provide him with a litter tray.