Please consider adding the support for "Non-scaling stroke" [1] from SVG Tiny 1.2 Spec. It could greatly help when zooming SVG content. [1] http://www.w3.org/TR/SVGMobile12/painting.html#NonScalingStroke
Unfortunately this is a pretty invasive change to the rendering code :( I agree it is useful though.
The main discussion is on bug 31438 now. *** This bug has been marked as a duplicate of bug 31438 ***