I do not know if you would consider this facts but it is what makes me think it is a good idea to have training.
1 - while having a discussion with a gun owner on this subject I gave him a scenerio. Basically wake up, leave room, BG standing here, do you shoot or not. They said ABSOLUTELY! At that point I said in the direction of your shot you have a seven yr old sleeping (literally a straight line). There response "I never thought of that"
2 - someone has been carrying for almost a year. When I went to visit I had to show him how to take down and clean his gun. If this person was in the same store when a BG came in would you really want someone like that to have a weapon?
Most people on this site a class would probably be a waste of time and money. But laws have to envelope everyone to protect everyone. And because of that decisions must be made for the person who might in one day decide I want a gun, buy one, and walk out with one on their hip.
I believe in the 2nd amendment. I also believe in laws to make the public safe as a whole. I do not want someone to drive 100 mph in front of my house. You need to take a test to drive a car. That right can be taken away. Why would guns be any different?