I just set two of these 100w led spotlights over a 220G 2 months ago, with dimable ballasts.
http://www.ecoxotic.com/catalog/prod.../89/image/393/
http://www.ecoxotic.com/aquarium-led...-pendants.html
-easily spreads the tank
-12" above the water and may be too bright (testing stage, currently dimmed to 75%)
-costs about $250 more then what I would have spend on MH
-way less heat transfer
-brings out corals colours better then any light I have seen
cannot comment on coral growth as of yet with these
Nothing wrong with MH, but so far these are proving to be better IMO.