The weight and bulk issue makes perfect sense to me. The GSW690 should be lighter than the original breech lock G690 BL which weighed about 4 lbs. Ever carry four pounds of potatoes all day in a back pack?
My walk about kit is comprised of a 35mm range finder with two lenses or DSLR with two lenses, plus a 6x9 folder. The antideluvian folder in this case is an Agfa Record III, which has a cold shoe to mount my Leitz 5cm finder.
When I need speed, I carry a 6x6 Agfa Super Isolette that has a winder with an auto film stop and unit focusing coupled range finder focusing. Both of which are lacking on the front cell focusing Record III, which has a non coupled range finder.
The Record III is slow going with regards to focusing, film winding and compositing. You do have to arm the shutter as a separate step. You can still burn through a roll of film in less than a minute, which is 8 exposures. I usually pre-focus, arm the shutter, wind the film and wait for the subject to move into the frame. Then at the last moment bring the camera up to my eye.
On the plus side, the Record III is compact and light. Too light, in fact, which is why I prefer using the Super Isolette that is heavier. So with the Record III, I try to keep the shutter speeds above 1/100th, which means there is only 3 speeds to work from. Now this would be a problem, but in a downtown area the lighting on the street can be pretty dim and the fact that I tend to shoot at f/8 to provide a margin of error while focusing on the move, both the subject and myself. In a pinch you brace an arm or elbow against a building or poll and shoot at 1/50th of second.
Lens resolution is a non issue with such a large neg. The exception being is that close ups at 4 feet with the 105mm Solinar are a bit soft, when compared to the unit focusing 75mm Solinar on my Super Isolette or Leitz Summicron, but older subjects love the look.
Another issue is film usage. If you develop your own film, six or seven rolls of film eats up a lot of time when in comes to D.I.Y. development. Six rolls yields 48 exposures. 35mm is much more efficient.
The Record III is no larger than my 35mm Canon P with a collapsible Summicron attached.