I do like the cooling solution on the Asus GTX 580 DirectCu but a 3 slot card makes it hard to do SLI.
I would go with the Evga GTX 580 1536mb GDDR5 $709 , Evga is a good company the has great tech support , customer service and quality video cards. I have always used Evga cards and when there is a defect the RMA they card without any problems , tech support is friendy , helpful and knowledgeable , as is the customer service. The double shot is just the fact there is two fans on the card. I have the 3gb version of the Evga GTX 580 , that could also be a consideration for you.