I do not know much about tins plugin, does it re-write the svg file?
If you ever do any CAD work then you are used to working in 'real world' sizes and CAD dxf and SVG files are both descriptive, can be text.
You can try and make sense if you look at the exported svg file which describes the vector in real world (inches) terms, which goes against the grain when "Gimp uses pixels" is fired at new users.
This one a 400x400 pix 4" x 4" @ 100 ppi with the path exported as an svg.
http://i.imgur.com/yB9Bz6M.jpgImport the same path into a new image 400x400 pix 2"x 2" @ 200 ppi and the svg still honours the 4" x 4" size.
http://i.imgur.com/Us844A8.jpgEdit the svg to the new canvas size and the path returns to what is expected.
http://i.imgur.com/E1LJj0n.jpgGimp to the rescue.
You can
drag and drop a path, from the path dialogue from one open image to another open image (same procedure as a layer). Gimp will scale accordingly.