Our Bro's over DriverHeaven have thrown up some FarCry Benchmarks which were run on a GeForce 6800 Ultra! Here's a snip! LOL
In summary, forcing the R300 path if you have a 6800 Ultra is advisable as it gives you decent performance however better IQ than the standard path.
One other point of note is that the Radeon 9800XT is very close in performance to the 6800Ultra at the same IQ levels. Only 7fps in average framerates separate the cards which is a phenomenal result for the Radeon.
In summary, forcing the R300 path if you have a 6800 Ultra is advisable as it gives you decent performance however better IQ than the standard path.
One other point of note is that the Radeon 9800XT is very close in performance to the 6800Ultra at the same IQ levels. Only 7fps in average framerates separate the cards which is a phenomenal result for the Radeon.