Ok I did some testing with my V5 and came up with these results;
System;
p3 600@800 on a bx
192meg cas2
V5@183, latest DX 8 drivers, 1.04 or whatever they are
Q3 verson 1.17, default config, standard HQ setting at 1024x768 with the texture slider all the way to the right.
refresh optimization off, depth precision disabled;
001, 74fps
Quaver, 65.8fps
refresh on;
001, 75fps
Quaver, 67fps
depth precision fastest;
001, 81.6fps
Quaver, 73.1fps
both enabled;
001, 81.7fps
Quaver, 73.4fps
above settings with texture compression off;
001, 68.7
Quaver, 55fps
From watching the demos run it seemed to me that the depth precision thing seemed to make the faster running parts of the demo run even faster, rather than improving the speed of the slower parts (showers of blood ect) but's that's just the impression I got, I could be wrong...
I don't actually play Q3, so I don't have any real "gameplay" experence to tell weather it's smoother/better in a "real world" suitation, most of the other games I play (apart from UT) are pretty cpu limited and are played with 32bit + 4xFSAA.