Tim, many other guys have carb heat working like a charm. I myself haven't flown those planes. Check out Jimbo's vids.
Yeah, but only on the Blenheim and the Br 20.
The supercharged engines (all other planes but the Tigermoth, think) did not need one.
Most likely the effect of flying through a cloud is overdone or simply modeled wrong for the supercharged engines.
Michael.