you could probably KEEP a lot of corals, but would they thrive and grow is the real question here. IMHO, i dont think that a lot of SPS corals would thrive under that.
watts per gallon is not a good way to estimate lighting. halides are a much more intense light than T5's are. so 250w of metal halide penetrates the water way more than 250w of T5 lighting. i guess i would say if you want SPS corals ... go with halides.
just my opinion, and many will probably disagree with it. i run halides and i keep ANY coral that i want under them.