Matt, from what I gather from various threads and from people "of weight", anything within the PAR bandwidth (400-700) nm ultimately behave the same with coral. We normally think of the photosynthetic curve with respect to chlorophyll, but various pigments, cofactors etc make other wavelenths photosynthetically accessible.
My intuition from what i have read on the subjects coupled with first hand experience with MH, T5HO, PC and LED seems to suggest that for a given PAR with an LED setup, you will get different results with a traditional reef light setup of equivalent PAR. It seems (again imo/e) that although there is the potential to grow coral well, the results are different (growth rates/coloration etc). LEDs can easily bleach out corals with far less "power" then MH/T5 (imo/e), but the spectrum REALLY matters(especially with SPS). I don't think that pumping up the blue to compensate the kelvin temp of the white is the best way of doing things. Yes, you can dial in your color, but I think we are really hurting ourselves with both the excessive yellow/green and lack of violet. This is going to sound odd, but right now, I think the LED solution is to mix the usual W/B LED mix and then toss in some super actinic T5HO (or better yet, 420 HVO).