To tight of a light spectrum depending on what materials the LED's are made of. Also, why don't they give the lumen output, scary. For that much cash ($189.95) pick up a 400w Switchable HID for a little less. I really don't think LED's are going anywhere, they are not even more efficient then a CFL for Lumen output per Watt used. Low pressure sodium would be the most efficient, but not for growing. So high pressure sodium would be the next step down in a efficient light source. Maybe Sulfur plasma lights will get better/cheaper soon??

Here is some Lumen's per Watt:
Candle : ~.3 (Lm/W)
White LED's : 26-70 (Lm/W)
CFL's : 45-105 (Lm/W)
Sulfur Plasma : ~100 (Lm/W) light output VERY close to sunlight, better than any other artificial light source.
High pressure sodium lamps : 140-160 (Lm/W)
Low pressure sodium lamps : 180-200 (Lm/W)