It's a 250 watt. I got a pretty nice 250 ballast free for taking care of this guys tank while he was gone for a week (he had recently upgraded) so I figure I should go for it. I'm going to use one of those overhanging fixtures so it'll be over a foot off of the water (hopefully). I really want to have a tank with a lot of light loving SPS so I'm thinking close to 5 watts per gallon.
I was thinking if I successfully manage the SPS I could sell some of the frags and make up the difference in extra electric bills with extra coral growth. I mean, 14 dollars for a 250 watt 14k of decent quality as opposed to 100 dollars for a light of slightly higher quality and slightly longer life span is well worth less energy efficiency. Just so long as its not ridiculously less efficient I'd say it's worth it.
The only reason I'm considering them is because I saw a friend's tank, who had his bulbs going 3 months in, and they were brighter than other 14ks I had seen, though with noticeable less blue (still quite a lot of blue, however). I'll see how it goes as I'm not planning on doing this until the growth in my nano gets out of hand.
True a 55 watt CPF produces similar spectrum, but it's going to be visibly less light and it'd take more than 2 of those to flood a 100g with light. (though I do know I'm going to have to bite the bullet when it comes to choosing halides over T5s or CPFs).
My dream is housing an obligate corallivore, though that's too far fetched for now for me to even consider for years.