I bought what I thought were some cheap Chinese knockoffs....that have PAR readings from 500 right under them, down to about 120-100 24" down at the bottom of my 100 gallon reef tank. I've had them since about March and been beyond thrilled with them. They are noticeably growing everything I stick under them.
I have 3 120w on my 100 gallon tank and 1 120w on my frag tank. I have some kind of encrusting montipora, I believe that almost died due to the heat...it bleached back to bone....and about a pinhead worth of color left. Thinking it was lost, I tossed it in my frag tank....about 4 inches below the surface....the light about a foot above that....and a week later the green and red was noticeably back. So I started to watch it closely...every day or two I could see it was noticeably brighter and had more flesh back. After about 2 week there is only a tiny speck of white still showing....and the red polyps are really standing out like they never did before.
I think this little frag wasn't getting enough light sitting too deep in my big reef but right under a strong light....it is doing incredibly. I have noticed this with several other things as well....as long as they are healthy when they go under that much light. Healthy Acan Lords....love it. Polyp like mad....colors intensify. But a couple Acans that suffered tissue loss from the heat....almost died in just a day of that intensity. The weak heads would whither but the healthy heads (on the same colony) would thrive.
Same with some Pocillipora...did so-so in the big tank....turned into a new coral in the frag tank.
If you are wondering....the water systems are different but measure almost identically. The frag tank gets too hot but seems to walk the tightrope ok.