Curtis--
This article will help explain some of what you are asking about.
http://www.advancedaquarist.com/2012/10/aafeature
I"ve mentioned also quite often that each coral needs a certain spectrum to get the best color/ flourescence for their particular pigments or chromo protens. If the light source doesn't contain that spectrum you aren't going to get the colors you want.
It basically comes down to having full spectrum across your whole tank and a high enough intensity to make that specturm show full effect. The article above explains this well. If a bulb has the correct spectrum it carries across the whole area of the bulbs light..........with LEDs it doesn't because they cast such narrow bands. That's why manufacturers try to cluster the diodes together.
You also need to have enough units over the tank to have the same spectrum throughout the tank to avoid those hot spots and dark gaps.
The worst thing that ever happened in the design of LEDs is that manufacturers allowed the user to dim and change the spectrum to such harsh degrees for the corals to look good to the eye. Again, the article above explains some of that well about our eyes and what we see.
Read this also--
http://capone.mtsu.edu/phys2020/Lectures/Part_1__L1-L5/Lecture_1/EM_Spectrum/em_spectrum.html
The problem with raising or dimming your LEDs is that everytime you do that you are changing the spectrum. It's inherent in the poor way these units are designed or maybe due to the limitations of how to control LEDs.
My best advice to anyone with LEDs is it to try to copy the spectrum layout of the 400w Radium bullb and then raise or lower the LED units. That way you are changing intensity without changing the spectrum.
I believe Kessils new 360 may be the first LED units that are capable of changing intensity without changing spectrum. Their tight multichip designs are also better than diodes that are spread out more. I have no experience with Kessils but have seen the 350s over tanks and they look good but I don't know anything about how they perform long term over Sps.
For you specifically, one option would be to just add a few T5's to fill shadow gaps & to also get the 420nm you want. This would be a lot more inexpensive that to continue to buy next generation LEDs until they finally produce units that can stand alone and color Sps correctly.
You could also look into doing a few Diy strips of LEDs, but if you're going that route, it's important to understand what you're trying to accomplish. A lot of the articles I have linked will help.
Another great article by Dana Riddle---
http://www.advancedaquarist.com/2012/12/corals#disqus_thread
Commercial LED units are slowly getting things right...........the problem is they are taking your money 2 to 3 times over in the mean time.
As far as some of the other newer generation units like the Vegas, Radion Pro, Maxspect Razor. Time will tell.........I'm still waiting on the results. Again best use would be to get the spectrum right and then play with height placement for intensity. What also is going to come into play is getting full coverage........do you have enough units over the tank?