I think that the GDDR3 memory is holding the true performance of this chip.
As i always have stated here, you need a monster bandwidth to run monster resolutions with AA/AF. Shading power is useful when you aren't bandwidth bounded.
The memory bandwidth of a gfx card is like a gold ingot. (do not mention the R600 please)
I just can hope that the 55nm refresh features GDDR5 with a 512bit bus -> 300 GB/s