I've never seen truly healthy growth with any LED. The plants always look a little strange. As long as they produce it really doesn't matter, but plants still prefer a balanced full spectrum light over just a few key wavelengths. No plant uses only 1 wavelength within a certain color. It (the sun) is always an infinite mixture of wavelengths (a range). It's like cooking with only salt and pepper, the food will still taste good, but not nearly as good as with all the other spices thrown in to it. Although a plant will grow with only the 420, 460, 630, and 660nm red wavelength, it would still prefer that it had everything in between as well. For this reason, I don't think that LEDs will ever fully "take over" the industry. The type of light that is really going to make a difference in the industry is one that uses little power "like LEDs", low heat, BUT ALSO PRODUCES A FULL RANGE SPECTRUM, with all the key wavelengths in between them.