Tom's hardware sucks ass even (their review has been taken down). There are
other reviews online.
I have yet to see the Radeon 3870X2 go up against two regular Radeon 3870's in Crossfire. I suspect that the results would be the same. The advantage the Radeon 3870X2 would have is quad GPU Crossfire potential and fewer slots used on a motherboard. The Radeon 3870X2 doesn't need a specific Crossfire compatible motherboard but two Radeon 3870X2's for quad Crossfire does.
Pictures of the ASUS model can be found
here.