There are tons of ways to light a reef. I used to use power compacts....about 5-watts per gallon on my 120-gallon reef. But I found that I was only able to get coral to do really well up towards the top of the rockwork. That was soft coral and LPS that I had. The bottom three qaurters of the rockwork was barren of coral in my 24-inch deep tank. There is a very credible member here in RC that has more than the 5-watts per gallon in a tank as deep as mine is, and says that he can grow coral anywhere in his tank and does. So it might be that you have to place tons of PC lighting on a deeper tank for that kind of result.
I've read in many places that t5 lighting is fine for reefkeeping and it's my understanding that it's used more widely in Europe...Look around this forum for other threads on this subject.
I changed over to metal halides, and I can tell you from my experience, that while power compacts were okay, I guess, for me for a while, the metal halides allow me to grow coral anywhere in my tank, including on the bottom and in fairly shaded areas. I have to say, in my experience, it's just an overall better option. Don't get me wrong, in a shallower tank....say, up to 18-inches deep, you can use power compact with more overall success than in a deeper tank. But, if you are committed to keeping a reef for the long haul, start with the metal halides so you won't be tempted to change over to them later on, especially if you may ever intend to keep SPS.