Interesting flying today, with both some low cloud around, and some taller snow showers.
The latter confirmed my previous experience that there's little (in this case, no) icing in clouds from which snow is falling -- they're already glaciated. I don't know enough cloud physics to be sure, and I certainly wouldn't want to bet my life on it, but it sounds plausible that supercooled droplets are not going to form snow.
Does that tally with your experience, Timothy?