You also have to understand that a large majority of TV and stage performers using headset mikes are also using in-ear monitors, too, and they don't even have loud monitors, or few speakers of any sort on stage.

This obviously reduces the tendency towards feedback or just plain weird sound while the mike picks up everything around it. Because of the small capsule size, even the best hyper-cardioid headset mikes pick up more off axis than equivalent hand held mikes.

Were I to try some of these out, at the very least, I would be recording my show, and comparing the sound to earlier recordings of hand held shows. Don't buy hype, be objective and listen critically. There's a reason that hand-helds still are the majority, even for top pros...