Why not use one (wisewatches?) in ordinary situaltions and noise-cancelling headsets or earpieces where noise is a problem?
Technically, noise could always be a problem. You never know where you might run into explosions and fire fights.
What about a privacy set that provides earpieces and hides the mouth and jaw, with sound cancelling that keeps the voice from spreading?
That would be option 1 (more or less). Secret Service agents can speak quietly into their mics in most settings, although they'd have to speak loudly in some settings (e.g., loud political rallies) to be heard over the background noise.