A Ti200-500 should be roughly equal to a 9100: faster with AA, slower with AF. More specifically, a 275/275 8500 should be faster than a GF3 Ti500, and a 250/250 8500LE/9100 should be faster than a Ti200. A 9100 will probably have better TV-out and signal quality at resolutions above 1024x768, and will definitely have better DVD playback.
If it's benchmarks you want, though, here's the best source I've found:
3DCenter.de's DX8 roundup. Ignore the German text (or use Google or Babelfish to translate), and marvel at the wide variety of games used (RtCW, Giants, Ultima IX, and more).