I used it before.
Growth:so so
Intensity of light: ....what's that?
Colors: I miss the colors I had then, best ever
If ya look for colors, I dont think there is any 10KK bulb out there to give ya such Greens and Blues.
If ya look for rapid growth go for lower K bulb
If ya're used for the intensity of 10KK or 6.5K bulbs you might think the 20KK is too dark, some people cant get used to it, some can.