The last few computers I've built I've thrown in Velocity 100's, but that was because I got them for 50 bucks each. Much more than that and you're looking at the same price as an OEM voodoo 3 2000.
If you don't use very high resolutions, a Velocity with 8M should be fine. I don't even know if the second TMU is disabled on mine because I lost my velocity CD and had to use the V3 3000's install disk.
But they are good cards if you can get them cheap. The one I have has 6ns Ram but the last one I used for my brother had 5.5ns. Not bad at all.