I went for a walk yesterday to experiment with doing macro without a tripod using my new R6II with an EF 100mm macro. Macro is a very difficult challenge for IS, so I wanted to see whether the much better IS in this camera, relative to my old one, would let me do without a tripod.
The answer is "sort of". I couldn't go to very slow speeds, but I think the problem wasn't IS; it was my own motion. Even slight motion forward or back ruins a shot because of the very narrow DOF. So as a result, I found that I rarely could go below 1/90.
The shot below is a wild plant in the rose family, but I couldn't identify it as to species. It was shot at 1/125, f.8, ISO 1250. Given that I wasn't focus stacking (which I would have done with a tripod), I should have gone narrower than f/8, as you can see from some areas in the petals. Still, this leaves me optimistic that in better lighting, I can manage sometimes without support.
Comments welcome, as always.