I can't compare, but I'll tell you why I'm going with Kessil. Early on, I went to a mini seminar from a LFS. He went into debth on energy spectrums. Kessil's spectrum was similar to MH. Both are similar to the suns spectrum in the lack of lower energy toward the red. Many forms of lighting have a bit of a bump toward the longer wavelengths (red). He claimed that this irritated corals. It makes since to some degree because that lower energy light would be as a result of being closer to the surface. Corals will want to limit the zooenthellae production when too much light is hitting them. The problem is that the lights we use are much less powerful than the sun. I see a conflict there. At that time, Kessil was the only light he knew of that didn't have that bump in the red zone. All that being said, there are plenty of people that seem to be doing a great job growing corals on most types of lighting.