I recently added support for the new SVG 2 'paint-order' property to Inkscape trunk (behind a compile time flag). Here is a short blog about the property. Chrome and Firefox nightly also support the property.
Nice one! However, what always makes me return to Oxygen is that most other icon sets are incomplete, and having 2 different styles, specially I'd they are very different, is not nice. Anyway, congrats! I'll watch this one.