I fly for a living and know several pilots in the area who fly for a living (some AF, some Marine, some Navy, and some only civilian time). We all will fly in cloud in an single engine GA. My sample size is small but I don't think that professional pilots as a whole are less likely to fly IFR in a single engine GA airplane. Icing is not IFR. If the plane doesn't have deice capability then don't fly in ice. Even in the middle of winter most clouds in the GA airspace in my area don't meet the requirements to make ice. There is risk to flying anything, the airplane doesn't care if it is dark or there are clouds (excluding those that lead to ice). If I didn't trust my plane enough to fly in the weather I wouldn't trust it vfr either; of course it is set up for ifr( if the plane was vfr only then that would be different).