I have always felt that open carry in public is a terrible idea.
If you are in your home, on your property, or in your place of business, that's different.
Just walking around on the street open carrying? Many of the people who do this are attention whores. If you are serious about self defense, get a quality gun, get a good holster, get some quality training, practice frequenty, and carry concealed.
The fact your weapon is concealed is a tactical advantage for you and I believe that it outweighs the potential deterrent effect of open carry.
You can only learn from experience if you pay attention!