I'm surprised to hear they produce lower quality output at small glyph sizes. Fragment shaders can do multiple texture samples and I've gotten very high quality

I'm surprised to hear they produce lower quality output at small glyph sizes. Fragment shaders can do multiple texture samples and I've gotten very high quality results. You can even do ClearType-style subpixel rendering with a handful of samples. The case where signed distance fields don't work is for large glyph sizes. They often end up chopping off corners or not having the density to represent thin calligraphic strokes.