My thoughts are this. Initially, it was a question of whether LEDs could even keep SPS corals. I think that question has been answered fully, else we wouldn't have local tanks like Juiceman's, Don Duncan's, Richard L's, and the myriad of others that have been using LEDs over their tanks for quite some time and keep a lot of SPS successfully.
Do they keep them better than MH, who knows... and honestly, if nobody can tell right now, then who cares. To me, that means that they can perform the same function and its just merely down to preference, or as Sascha highlighted, economic pressures. If one was superbly cheaper than the other, with both giving roughly the same results, then to the cheaper option the crown goes.
My preference between the two is MHs. Just purely preference based (okay, a tad economically-based as well since I don't have $1k-2k to drop on new LEDs right now, I'd rather get a larger CaRX) but I just enjoy the full spectrum lighting more. It might just be in my head, but to me, I see gradations of color better with MHs versus LED tanks that I've seen. It's no knock on the tanks as they are stunning, and the LEDs really make the colors pop on the SPS, but to me, I miss out on the subtle changes of color... the more natural look... the subtle hues of color... that I feel you lose out on with LEDs since they are so spectrum-specific in their color reproduction. The best analogy I can think of is digital versus analog... you want 420nm on LEDs, here it is... bam, exactly 420nm. You want 420nm on MHs... you get some 410nm... some 430nm... etc. You get the full spectrum with the focus on 420nm but also everything close to it as well. I may be rambling here, but I feel like there is much to be appreciated in between the wavelengths we desire and the wavelengths we also get in a full spectrum lighting source versus a more precise lighting source like LEDs.
To be honest, I actually prefer the colors of SPS I see under T5 the best, but I just don't want to pay for 8-10 bulbs each year at $25/bulb and it drives me nuts that you have to have every bulb perfectly positioned or it won't turn on, but that is another gripe for another thread.
I appreciate people's passion for one lighting technology or the other... for me, I'm not a fanboy of one or the other. I just appreciate what I get from my MHs and if someone gives me some free LEDs to throw over the tank, I wouldn't turn them down either. If I like the look, I'll keep it. If I don't, I won't. It's that simple... either lighting choice though, I know it'll grow my SPS and they will look good under either lighting, it's just whatever my preference may be for the look of the tank.