In a nutshell EVGA's 9600 GT SSC offers about 6% more performance for a 6% price increase over the reference design 9600 GT. This ensures that the cards shares the number one performance/dollar spot with the reference card. Since the performance is higher, but the power consumption is only slightly increased, EVGA's card can also claim the number one performance per Watt efficiency spot.
Overall this shows that EVGA knows exactly what their product can deliver and how the competition is positioned. Combined with the EVGA limited lifetime warranty this should be a card that you can easily use for a year or two.