The soft gold mixes silver and gold with much higher reflectivity than the white surface. It is called soft gold because the mix of these two colors results in a slight warming effect, which is often desirable for shadows. Outdoors it is excellent for use in open shade, where there is no direct sun. The white fabric in open shade likely doesn’t have enough reflectivity for the results you need, so the higher reflectivity surface will work better. The soft gold is also great in open shade caused by foliage, due to the greenish cast in this light. The warming effect gives a more pleasing light quality. Be careful using the highly reflective fabrics in direct sun when bouncing light into people’s faces, as you can blind them, but for outdoor rim/back lighting, this is an excellent choice. In the studio, the soft light from soft boxes is more like open shade & the choice between soft gold & white or other fabrics is more determined by your artistic vision & sometimes the white surface is not as reflective as you need.