hid lamp

Just wondering what benefits is their of induction lighting these days and why do some buildings use it, such as the Philips induction lighting that is used to light up the faces of the Great Clock of the palace of Westminster (Aka Big Ben). The article below lists several benefits of induction...

I don't know how much additional power percentage wise relative to the bulb a SOX lamps ballast takes up, but can LED's achieve the same or greater lumen per what ratio that Low Pressure Sodium/SOX achieve? I am well aware of the awful colour rendering and CRI of SOX lamp's mono chromatic light...