I've flown with flashlights many times, even had an Italian "tsa equivalent" look into my 2000 lumen Fenix and turn it on to make sure it was a legit flashlight, bet he won't do that to any light again. He quickly turned away, blinked oddly several times, and put it back in my bag.
That being said, I've never even tried taking a light with a crenulated bezel in my carry on. I would be cautious. It may pass, but if an over zealous agent wants to make the case that it's a weapon it will be easier for him to make that case with a crenulated bezel.