I haven't flown internationally since I got my provari. When I went to Canada, I just had my eGos at the time. They were in my carry on and I had zero issue.
When I went to Boston last month, I brought my provari. I had it in my carryon. I made sure to take the batteries out of it, went through security twice without any hold ups. Not so much as a second look.
I think it's really dependent on how well trained the TSA is and how good of a day they're having. If you get stopped you may need to explain what it is, but once you do, I'm sure they'll understand. Word of advice. Don't bring any filled tanks. Every time I have, they leak because of the altitude.