I own a Surefire E2D. I travel all over the USA and Canada for my work. I never leave home without the E2D with the Crenellated Bezel. I loathe traveling by air. But I'm not skilled at doing anything else other than what I'm currently doing. So it is the price of doing business, unfortunately.
I just take all my stuff, pens, lights, keys, watch, etc and put it in a plastic bag and insert it in my carry on suitcase and run it through the TSA scanner/X Ray machine. I travel at least 20-30 times per year and have taken that light on every mission.
No one has every taken the light out of my suitcase and questioned me - yet. Once years ago before I started using the current system, I threw it in the round coin and key dish along with my other stuff. An agent picked up the light and said "what do you use this for?" I said "to see in the dark!" Then he progressed: "why do you need this on this flight, and I retorted for the same reason I sit in an exit row aisle seat, the same reason I wear a seat belt, is because if there is a castostrophic failure of this aircraft I want to be able to find my way out of a smoke filled cabin in total chaos." The Agent, avoiding this convesation from going any worse in front of hundreds of people said, "okay sir" Case closed.
I've carried it in my suitcase ever since.
I've been in most of the 50 states and never once in three years been questioned about the light. I blend in with the rest of the non-professional nitwits and look like a typical vacationer. I've never had a problem.
But I carry a Fenix AAA light as a back up in the event I lose my Surefire to TSA. I suppose it can happen but for me it is the price of doing business in this economy and security climate. Unfortunately in my profession one doesn't make a lot of money. But in spite of that, I'm not leaving home without some basic tools just because I'm afraid I'll lose them. I actually use these tools daily and am not going to deprive myself because I'm fearful someone might take it. They might, again - the price of doing business in this world. I just pick up some more pop cans and save my pocket change and order another light when I get home.
At this point...I'm tired of living in fear and wonder about all the "what if's". I"m not advocating anyone else do this...but if it isn't illegal, immoral, or not against any rules I'm taking it...if it gets confiscated by someone thinking they're saving the world then so be it. I have a back up and I have a work around plan - I just Charlie Mike.