You can definitely keep sps under 150w halides. We in America tend to go high wattage to keep sps(they do have the best colors that way, typically), however if you look at alot of tank specs from Japan and even some in Europe smaller wattage bulbs are often used. I'll try to find the link, but I remember one tank that was breath taking. It was a 360 gallon lit with 8x70w halides, a couple SHO and several vho actinics. Of course all the acropora were at the top.
That said, I am a 250 fan, but that just goes with the fact I'm an acropora fan. My 80 gallon is lit with 2x150w halides and 2x130w actinics. My avatar is of a patch of superman montipora in the 80 that is 26" below the halides growing about .5" a month(radius, not diameter). I also just rescently had to move a purple stylo frag that was too close(pasteling-out) at about 16" from the bulb. Since moving it lower, it's deep lavender is returning.
Long story short, just watch your placement, and realize acroporas might not color up for you unless they are directly under the bulb as high as possible.
