This notion of blinding people is very interesting for the Aurora theater situation. Going through the Terminator, Clint Smith explained to us how his champion groundskeeper (who happened to be a fine shooter) would single-handedly take out SWAT and other tactical teams and sometimes survive, but against 1 and 2 man situations, virtually never lost...all during night ops, him with a pistol and the tactical folks with their pistols, or even semi-auto or selectfire long guns (simunitions). Being "blinded" wasn't a problem despite not having the benefit of a giant screen playing a movie to illuminate the Terminator for him and he didn't use a light.
People talk about disorienting strobes. Great. I have strobes on a few lights. I hate them. The really good ones make for a stop action animation that can make it difficult for me to track moving targets. As for the affect on people, sure, it may bother some, but most folks really aren't bothered. My kids used to take my lights to use the for their dancing. They liked the effect.
So you are in the theater and you breakout our your mini tactical light to blind and disorient the shooter, but you are still in the middle of the seats and your egress is based on the people to either side of you getting out first, maybe those in front of you if you opt to go over the seats. The gunman sees the light because it is in his face. Where will he be shooting? Sure you can protect yourself. Hold the light high and off to the side, FBI style. That way you draw fire to the people behind and off to the side of you. Great job. If I am behind you and I see you doing that, because I can't stop the shooter as a regular patron there, then I am stopping you from your stupid tactic of holding a light up in front of me that may get me killed.
You want to blind the guy for a few seconds, but you are in a theater full of people for a new movie opening who have managed to panic their way into disorder, trampling, and general lack of control. He already knows where the exits are and being "blinded" won't keep him from seeing the EXIT signs and just shooting a few feet below the signs. The light hasn't stopped his finger from pulling the trigger. On top of that, the movie screen is going to be putting out a lot of light from time to time, maybe during the current scene. He will see a lot more than you think. This isn't a one-on-one situation where you throw down your magician's instand smoke and disappear in a flash and puff of smoke.
In a less than lethal situation, a powerful LED light in somebody's eyes does a good job of disrupting their OODA loop.
You think he will stop pulling the trigger because he is afraid of hurting somebody that he can't see? No, he will just respond to the threat and shoot at it.
Remember, the light can't be counted on as a weapon and the gunman can't be counted on to respond like a deer in headlights.
The notion isn't too far from Dan McKown who is credited with "stopping" the Tacoma Mall shooter by yelling at him. Sure, the shooter was distracted and stopped shooting other people and then pumped 3 or 5 rounds into McKown and then retired to a music store. McKown is a cripple for life. Words or a flashlight does not stop physically stop people from being able to pull the trigger.
Having a flashlight is a good thing as you are apt to be able to use one several times a day and you may need it to save yourself in some situations, but question its effectivity of being able to be used as a light weapon and understand the rammifications of the various results that may occur, including drawing all fire toward you.