That's actually called brandishing and it's illegal. You should only pull a gun if you intend to kill someone as a last resort. Not wound, not threaten, kill.
Again ... depends on state laws. In TX you don't shoot to kill.
You shoot to stop the threat. You don't shoot in the head either, intentionally, that implicates execution. You shoot center mass.
This is what the instructors teach in the licensing classes. It's also worth mentioning, you must take a training course which will familiarize you with all of the state laws and prove your profeceincy with your designated firearm class (semi-auto or revolver) before you can even apply to the state. After applying to the state, you have to pass an extensive background check and be paid upon your property taxes and child support is applicable.
That aside .. rather or not it's worth making a shoot over camera gear or not is up to the individual holding the amera and in that situation. Being a hobby to me, probably not worth the shoot. If I had $6k wrapped up in what I was holding and that much more in my bag that the BG was wanting, and I depended on this for the livlihood of my family and myself, well that may very well be reason enough for me to take someones life. You have to consider, is it worth preserving some low life's life who's wasted thier mind, thier life, thier sanity away over the use of drugs and a string of bad decisions over you own ability and means to provide for your own family if you have all of your resources invested in your gear?
At that point, I look at it as, either his life or my families well being.
Now .. all that being said, there are WAY to many variables to ever be able to say with certainty that a given situation is a good time to shoot, however given the oppurtunity, I would not hesitate defending myself or my family with deadly force if put in a situation where I deemed it necessary.
Sorry for the long ramblings.