I've been reading this thread with some interest. If I have detectable nitrates, my PE goes away, as well as growth and color. If I keep my phosphates at the bottom edge of detectable and zero nitrates everything grows like a weed and the coloration is very good.
I had an excellent DIY LED setup, but even though I had the identical spectral coverage as a Radion (long before the Radion) and others, my corals would either just brown and die or grow a little, stop growing, and eventually die out. Some corals like stylophora were OK, granulosa and others were NG. PAR was adjusted correctly as well as my daylight period.
After seeing the results of a university study that was published last year regarding LEDs/MH/T5/plasma that showed a consistent SPS mortality rate under LEDs of 50% or greater, I switched to T5 and was astounded at the difference it made in my tank regarding growth, PE, and color. I'm now growing SPS corals that look as good as some of my local guys that sell frags on Fragswapper for hundreds of dollars.
I think that as LED's get better and better, they will dominate the hobby like T5/MH does now. I'm not sure that we are there yet. So, please post up some progress pics of your tank as things move forward. I'm really interested in how things will go. Otherwise, your original question was extremely well formulated and you received some great answers.