...this is the first I've heard of the 'double-inhalation' stealth technique. I tried it (didn't read a manual or anything, but was pretty self explanatory) and it works amazing. Easy to have virtually no vapor.
The second I read that I tried it. Holy crap, that is really amazing. I also don't really have a need to stealth vape regularly (can vape all I want at home and work) but I imagine it might come in handy at some point. Might also be handy in exhibiting to someone that it IS NOT smoke. Pretty sure you can't do that with a cigarette (though I'm not going to go buy some to find out for sure).