I just tried Xbench 1.1 on my WD 8Meg cache and my Quatium 7200 2 meg cache, there both running OSX 10.2.6 and the WD has a score of 90.66 and the Quatium has a score of 82.81, The disk test on the WD is a 108.45 and the quatium is 56.88.
I've found Xbench to be very unreliable - it gives wildly different numbers between runs on the same machine: One run, I'd get a 68.35 for the machine number, on another, 74.15. On one run, 534.81 Mflop/sec for vecLib FFT, 1.52 Gflop/sec. WTF?!