From the specs the XFX is better, more power, plus as @Rugger said they are made by seasonic, like many corsair psu's, and you get the 5year warranty.
If you want go look at some other psu's, from Antec, Corsair, or seasonic, but the XFX is fine.
According to this review http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=225
the card has 44A on the 12V rail, or in other words 528watts on the 12v. So that should solve the confusion.
Reviewers say it is good, it got a 9 from the link above.
Hope this helps!