I'm a MH fan, too. I run 250W DE's (Phoenix 14K's) with VHO supp on my SPS tank, but know someone running T5's and having great growth and color.
As Tomoko mentions, stable parameters, esp. Mg, Alk, and Ca (assuming NH4, NO2, and NO4 are well under control) are important for SPS. Invest in some test kits (I like Salifert). PO4 can also cause issues for SPS. Unfortunately, hobbiest test kits aren't the most reliable for PO4. Good, alternating current is also important (tons of flow, but in all directoins and not directly on anything). Nothing like colored sticks...