Comment 4 for bug 1396582

AFAICT not directly an Inkscape bug: based on tests with local builds (on OS X 10.7.5), whether or not it reproduces with Inkscape 0.48.5 and current trunk r13803 depends on which versions of upstream libraries are used.

Not reproduced (Inkscape. 0.48.5, 0.91+devel r13803):
- cairo 1.12.2, fontconfig 2.9.0, freetype 2.4.10, pango 1.30.1
- cairo 1.12.14, fontconfig 2.9.0, freetype 2.4.10, pango 1.32.5,
  harfbuzz 0.9.14

Reproduced (Inkscape. 0.48.5, 0.91+devel r13803):
- cairo 1.14.0, fontconfig 2.11.1, freetype 2.5.4, pango 1.36.8,
  harfbuzz 0.9.36

The difference in the generated output appears to be related to the font type: OTF affected, TTF not.

The resulting effect is possibly related to changes in upstream libraries (freetype, or cairo), as discussed in a similar poppler bug report earlier this year describing the same visual effect (darkened rendering of text at small sizes with OTF fonts):
poppler: <https://bugs.freedesktop.org/show_bug.cgi?id=78990>
freetype: <https://savannah.nongnu.org/bugs/index.php?42406>

In Inkscape, the outlining of text via PDF export option is eventually done by cairo (with information about the font from "the underlying font system"):
http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/view/13803/src/extension/internal/cairo-render-context.cpp#L1618
http://cairographics.org/manual/cairo-Paths.html#cairo-glyph-path
whereas 'Object to path' uses internal functions:
http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/view/13803/src/path-chemistry.cpp#L509
http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/view/13803/src/libnrtype/Layout-TNG-Output.cpp#L761
http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/view/13803/src/libnrtype/Layout-TNG.h#L375