For what it's worth, there is a big difference between cutting wall and floor tile. The floor tile is fired at a higher temperature and is much harder.
For wall tile, you can cut curves with a Roto-zip or Dremel tool with carbide blade very easily. One way to cut curves in floor tile is with a scroll saw with a diamond blade. You might check with stained glass suppliers as they also use similar saws. If you try to cut a floor tile with a rotary tool and carbide bit, it just throws a few sparks and the tile will not show much indication.