IS all the way...
I shoot with a combination 17-55mm f/2.8 IS and 70-200mm f/4L IS lenses on a pair of 7D and 7D2 crop sensor cameras. I would not be without the IS capability. IMO it is worth its weight in gold. I also have a 100-400mm f/4.5-5.6L IS Mark-2 lens with IS capability. The new IS is just terrific,
IS frees me from needing relatively bright light when shooting at long focal lengths. It also allows me to shoot at a far slower shutter speed in lower light. Granted, IS will not stop subject motion but, as a photographer for over 50-years now, I can work around subject motion. However, besides using a steady rest, there is no work around for camera shake.