I thought I would pass along the benefits of my rather time consuming search for a camera bag for my Sony A7R kit that would meet four goals:
1. VERY light weight.
2. As small as possible, yet provide quick and convenient access to the camera body with a mounted lens and two additional lenses. The FE 24-70mm zoom, the FE 55 f/1.8 and the FE 70-200mm zoom.
3. The ability to store the A7R with the 70-200 zoom mounted on the body, or alternatively store the 70-200 zoom separately. This is important to me as I would not want to be forced into changing lenses in order to store the gear.
4. Comfortable to use for walking around a city while traveling.
The bag that I finally found that meets the goals for me is the Lowepro Transit Sling 250AW at 1.7 pounds.