But if they -- at least "quality" brand LEDs -- don't have really long (useful) lives, the cost premium over other types of light bulbs looks much less justifia

But if they -- at least "quality" brand LEDs -- don't have really long (useful) lives, the cost premium over other types of light bulbs looks much less justifiable. (For reference, according to http://www.lighting.philips.com/main/support/support/faqs/life-and-light-output/why-is-the-life-of-leds-measured-as-lumen-depreciation http://www.lighting.philips.com/main/support/support/faqs/li..., "The normal convention is to measure the life from when the output has reduced by 30%, i.e. when there is 70% light output remaining.")