I don't think you'll find many proponents for LED grow lights, at least not here. They generally lack the necessary output to be beneficial enough to use.

I personally stick to the K.I.S.S. principle and the belief that if it ain't broke, don't fix it. Until LEDs are proven superior to HID lighting, or even fluorescents for that matter, I wouldn't even give them a second thought.

P.S. I just read over the page you linked and nowhere do they come close to stating the output of the LEDs. For a $180 light designed and sold as a 'grow' light, the output is something that should be listed. They do say that they are '10x as efficient' so they output as much as a '400w HPS', which doesn't seem the most believable.