I have heard mixed reviews on the duorb... right here on this forum actually. When 8800GT was new and overheating stick I remember some people critiqued the duorb claiming it only had one heatpipe.
Actual performance, I cannot comment.
With the exception of the HR-03's it is the best cooler for 8800GT's and 8800GTS 512's.
With the exception of their watercoolers, Thermaltake makes quite a few top notch products.