Who is to say r600 is going to fly on DirectX9?
What if their true strength is DirectX10.

Look at this the G80 uses 128 stream processors.
AMD uses 320 (Probably more inefficient than Nvidia) the DirectX10 format is made for using a unified structure, DirectX9 needs a converter to translate to the unified shader system (Which might become more inefficient with more stream processors).

Don't say its a failure till we see benches of Both DirectX10 and DirectX9.