Instead of a 256-bit memory interface like the (9700 series), the 9500 series has to make do with 128-bit. 4 pixel pipelines are stripped away in the 9500, The 9500 PRO, however, gets the full 8 pixel pipelines and 128 MB.
9500 PRO, the memory bandwidth is 8.8 GB/s, due to the memory bus, which has been reduced to 128-bit (from the 9700). The fill rate (2.2 GPixel), however, is identical to that of the 9700. With the 9500 (non-PRO version), the fillrate is reduced to 1.1 GPixel, due to the 4 pixel pipelines that have been left out. Here, you can expect dramatic slumps in performance.
If you can afford it i would go for the 9500 pro.