Awesome article. I will like to add that measuring LEDs is definitely more difficult than MH. Since MH light is broad spectrum with minor concentration on certain wavelengths, a standard PAR meter works great. Since a properly designed marine LED system uses LEDs with wavelengths that are aimed at coral zooxanthellae's photosynthetic peaks in massive amounts - this quickly saturates a standard PAR meter's sensor.
The proper tool for measurement would be the radiospectrometer. Yes a 10X intensity increase when compared to MH is a bit high, but not as outrageous as you may think. MH outputs light across a huge spectrum from ~380nm - 800nm+. Lower wavelengths take a significantly larger amount of electricity than the higher wavelengths. Note: that is not all usable light to corals. Corals typically absorb the light in the wavelengths where their photosynthetic peaks lay, everything else is reflected.
I can't speak of the Cree LEDs - we only sold those for a while, and had a huge issue with reliability from them. The Luxeon ES (and latest version of the Rebels), when measured in comparison to a very high end MH bulb, while using a radiospectrometer in the chemistry lab at the University of New Orleans, showed that the Luxeon ES fixtures that Steve's LEDs makes, using our custom LED combinations - has shown that they actually output about 8.2 times the amount of "usable" light than the MH. To define "usable light" I mean producing light in massive amounts at specific wavelengths that corals can actually use to photosynthesize and grow. Granted, the MH and LED overall lumens comparison results in LEDs being only ~2.1X more efficient at creating light (heavily depending on the manufacturer and color temp of the MH bulb. But in an aquarium, the whole purpose of selecting a suitable light is to find something that 1) makes corals grow well, and 2) makes corals look awesome.
That said, a good LED system will be able to do everything a traditional lighting fixture can, all while having an even brighter appearance than MH, T5, or any other lighting system, all while providing a significantly higher amount of usable light.
Here's the kicker: MH bulb manufacturer's specs - although seem amazing on the box, start to degrade almost immediately, within a matter of hours. So MH posted specs are only valid moments after plugging them in, and degrade dramatically, where the bulb is barely even usable after 1 year necessitating yearly bulb changes. LEDs have negligible degradation, and remain usable past the 15 year (24/7 operation) mark. All the while consuming significantly less electricity and outputting much less heat.
In conclusion, I love LEDs because they are awesome.
Jeff