I've been reefing for over 30 years, and anybody claiming that metal halide is a bullet proof solution for reef tanks is wrong.
I hate bad science, and reefing forums are full of lighting science myths that would flunk a 6th grader out of science class. What I hate more is revising history.
15-20 years ago before we had LEDs we had mostly metal halides with fluorescent tubes being the new kid on the block . The reason we were flocking to tubes is we were tired of killing our SPS every time we changed halide bulbs due to horrendous spectral differences in new bulbs vs old bulbs given reef halides were'nt manufactured with enough volume to keep proper Q/C deviations. Changing halide bulbs on a reef tank were like changing fuel rods in a nuclear reactor and done with a lot of shaking and sweating...except I think the Russians had better quality control. With a LED light I can turn the thing down to acclimate coral. Not possible with tubes or halide. Frankly I love the look of a good halide tank because the LED equivelants like the Kessil don't have the color mix down. Otherwise the most vigorous and healthy SPS tanks I've seen are lit with chinese black boxs.