Tangentially, I'm working on a little patch to pixman that enables font rendering results that look like the upper samples (default rendering is on the bottom):
There is no hinting of glyph shapes here, just gamma-corrected compositing from sRGB surface to sRGB surface with freetype's light lcd filter to ensure grayness of the composition results. You should be able to see that the default code as a rule produces too dark rendering results. (And the default lcd filter chosen by cairo generates other kind of color fringing at the smallest sizes, but that is separate topic.)
Merely getting the gamma-corrected compositing right should improve results considerably, especially for small sizes where the error made is the greatest, as can be seen on the darkening and color fringing that results.
That is Liberation Serif, which I found very pleasant to work with by the way, both for this subdivision modelling and classic low resolution 2D rendering. Sad to hear its not to be updated. The name is great, it would be a shame if that got locked up and died.