I had both a GW670III and GSW690III at the same time. They make a great pair though if I did it again I'd get 690s for both. I later sold the GW as I got a Mamiya 7. But I kept the GSW. If I could only have one , esp. for landscapes, the GSW would be my choice. It works ok for candids/environmental portraits too, and the neg is so huge cropping is no problem if need be. Stopped-down, the GSW holds it's own sharpness-wise with the Mamiya 7 lenses, I think.

-Ed