I have to say, it would be pretty interesting. I know you're anti-gun Johnny, so you naturally assume that all gun owners are idiots eager to get their gun off, but I don't think this would happen. Since you've probably only had experience with guns in movies and video games (like most gun-control advocates) let me share some basic gun-safety rules I learned from about age 9 starting with my BB gun and a bit later in hunter's safety class that apply to this situation:
-Never point a gun at anything you wouldn't want to shoot.
-Never shoot at anything without knowing what is BEHIND that object.
-Always clearly identify a target before shooting it
-Always be sure others are not near the target or the muzzle of your gun
Next is a lesson from CCW class:
-Escape or avoiding conflict is always the best option
-Never use deadly force (a gun) unless your life or someone else's life is in danger
-Be sure you are not making the situation worse by using deadly force, whether that is escalating the situation, or hurting innocent people.
Because of these lessons, CCW has an excellent safety record. MOST people who have CCWs would not just stand up and start spraying bullets like an idiot. Is it possible? Sure. It's also possible that Police could act like idiots and shoot innocent people:
In LA:
LAPD, Torrance Police Shot At Innocent People In Frenzied Hunt For Former Cop Christopher Dorner
In NYC:
Was The NYPD Responsible For 10 Of The 11 People Shot Yesterday? | Zero Hedge
My point is we're all humans, we all make mistakes and we all might interpret that situation a little differently. But we still have the right to defend ourselves.
I have to be honest, when I heard about the CO theater shooting, I didn't think that was a situation where a CCW-holder could have done much. You've got a dark theater, with dozens of people panicking and (supposedly) smoke grenades. The guy is ripping-off hundreds of rounds a minute (supposedly had a Slidefire stock). It was probably over before anyone realized what was happening. And it would be pretty tough to single the shooter out and stop him amidst the chaos. BUT I wouldn't blame someone for trying. If I DID happen to see him and I had a clear shot from a reasonable distance, hell yes I'd take it! It's better than just waiting to die!
Also, remember most of these guys are cowards and the minute they know someone else has a gun, they're likely to just shoot themselves, like the guy at the mall in Oregon. I'm not sure if the shooter would even notice in that dark theater, but you never know.