The LED system would solve a lot of CORNER tank issues... you could design an LED pattern that would cover the entire tank evenly.... which is something that most of us struggle with...
That being said, until some one can do a spectral analysis on the output of LED systems, and show that they are capable of meeting the needs of corals, for me SPS specifically, MH are going to stay...
Now what was really interesting, was the second article... which, after the first two pages of reading, is claiming that sufficient PAR will be better than correct spectrum for growth and health of corals... There's a lot more thread to read on that one, but when you combine the two threads, with info thus far, LED's can get you sufficent PAR (250w MH equlivilant) then it should be sufficent...
I'm not saying it will produce the mind-blowing colors like some spectrums, but again, looking at the LED thread, it also appears that you can get LED's for many spectrums and as such, create a completely custom LOOK to your lighting solution, i.e. balanced spectrum, and achieve sufficent PAR...
It's got me very interested... for two reasons.. first, as above, if I can design a lighting system that hits all of the tank evenly, then that means more corals for me.. and second, LED systems, in theory, can last for years and years... again, no one has done a proof-positive that the PAR levels are sustained, and that the spectrum of light hasn't shifted in LED's... just that they are "on" for 50,000hrs... obviously not enuf data yet to make me switch.