The problem with the gray tones is that they work well only at 72 points. They also consume huge amounts of memory, and they make the file sizes absurdly large. The glyphs for this font look much better as 280 pixel high clipart. If I do fonts from this type of artwork again, I'll abandon the grey tones, and concentrate more on maually definining the black and white areas, rather than using a 16 colour or 256 colour bitmap intermediate stage.
As for parallel stripes for gray tones, I did use this a bit in ObeyRockers, but it only works for small areas.
Thanks for the comment.