Also for those who don't want to convert, Thin Lite sells LED versions of many of their fluorescent fixtures, a bolt in replacement. In the case of my recessed 15" fixtures, the LED fixtures have a variable brightness feature-and according to Thinlite are brighter than the fluorescents. OTOH while the LEDs are likely bit more efficient, and better at directing the light downward, the fluorescents are certainly not inefficient. I would have changed them a long time ago if they were. Also fluorescent light quality is nearly up to par with LED if you select the right 800 series lamps.
Also Thin Lite LED can be specified in several color temps including 3000K. You may need to contact dealer and special order. Default is 4000K (cool white).