Yes the Black Magic fans have a great CFM rating, but they come without shrouds so there's no guarantee they'll flow that much on your car. Plus, you can get fans that flow more air for half the price and were tested to go over a 100,000 miles.
How about giving us some examples? Have you ever used or known someone who has used a Black Magic fan? I know a few people with them and none are dissatisfied. I do agree they don't come with shrouds, but then, since the application is going to be a custom one, that would be difficult. Shrouds are cheap and easily made.
