Windows 7 64 bit
NVidia GeForce GT 425M
When trying to render to svg, the resulting strokes always have the Base Color as set in Freestyle Line Style under Color instead of the colour resulting from modifiers, like Along Stroke or Material.
Exact steps for others to reproduce the error
Create a scene with a few objects which have a Diffuse colour
Enable Freestyle and Freestyle SVG Export
In Freestyle Line Style (in the Render Layers tab), click Color and add the modifier Material
Set to Mix and Diffuse Color (if you used a diffuse colour on that material, the bug appears with either Specular or Freestyle Line)
Change the Base Color so it's not black
View the resulting svg file in your favorite svg editor: the strokes all have the Base Color instead of the diffuse material colour as expected
When selecting Fill Contours in Freestyle SVG Export, the filled areas do have the correct material colour but the strokes are still in base colour
I don't know if this is really a bug since filled areas (when that option is selected) have the correct colour so that the outlines of the shapes are visible. But I have an application where only the strokes are used (and their colour). In that case consider this a feature request where you can apply a custom (preferrably material) colour to strokes.