Originally posted by timn421 I'm just trying to get an idea/opinion of which system might be better for me in this regard.
Sensor stabilization is done by having the sensor move to adapt to camera motion, does not correct lens motion effectively (that's why Panasonic have been working on combining both sensor stabilization and lens stabilization). The gap between camera motion and lens motion gets smaller when the camera body and lens are balanced (wildlife shooter know this as they adjust camera/lens position in gimbals so that the system doesn't move when we stop applying any force). Typically, the Pentax K1 and WA lens system is more balanced than the equivalent Sony system, because the small size / weight convenience of the Sony bodies turn out to be a disadvantage for stable shooting without tripod.
I shoot with the K1 + battery grip and the D-FA15-30 with SR enabled in low ligth, I get sharp images with 1 sec. shutter speed. I use the K1 II hand held pixel shift and it gets me one or two additional ISO stop improvement, say shooting at ISO 400 gets me images as good as if they were shot at ISO100.
There are now a lot of museums that do not allow use of a tripod, the most popular idea from mainly photographers (canon, nikon) is that tripod is what gets pro images, so they forbid tripod and to get tripod allowance one must file a pro photographer registration, but Pentax flies under their radar: I go around the "tripod not allowed" interdiction by using K1 Mk II, with battery grip loaded with 6xEneloop Pro, and D-FA15-30, HHPS (most people have no idea how good the K1 Mk II is in low light).