I'm doing something really similar, but creating a multi-resolution ICO.

    inkscape icon.svg -w 64 -h 64 --export-type="png" --export-filename=- --export-area-page | convert - -define icon:auto-resize=64,32,24,16 favicon.ico

Pretty sure that it's more efficient to have multiple files but, whatever. Multiple favicons annoys me.

The nice thing about using Inkscape like that is you can easily loop it and generate a number of icon sizes. Since they'll be rendered at the size specified there's no scaling artifacts. An icon might look bad because it's too busy for a 16x16 square but at least your colors won't bleed too badly.