I think it's pretty obvious that the 1Ghz board is going to run everything faster than the 800mhz or the 600mhz boards.
How much faster, I don't know. I wouldn't expect the 1Ghz to be 20% faster than the 800mhz board & 40% faster than the 600mhz one, though.
But it would make for an interesting comparison. You've got my curiosity piqued now.