[BennyB]

I think the breath helps pop the larynx open earlier, which in turn triggers the rest of the body responses that tell the unconscious person that they are ok, as well as supplying air a little bit earlier.

This is what I heard at the comp in Nice earlier this year from the French guys. I can't see any reason why it would either not work or make the situation worse (besides the diver waking up to someone kissing them... which could work both ways!). All the things you've mentioned (talking calmly, blowing on face etc) are all part of an overall response to regain consciousness, as I imagine the quick breath is.

Cheers,
Ben