If you don't conceal your weapon, you give up the element of surprise in the event you are attacked and need to defend yourself. However, by carrying your firearm openly, you may deter a crime from happening in the first place, which would then lead to a better outcome. It is difficult to determine exactly how many crimes are deterred each year by those who carry openly due to the obvious fact that in such circumstances the crimes don't even take place.
We do however have at least one documented example in Kennesaw GA where a crew of armed thugs decided NOT to commit armed robbery in a waffle house because the thug who went in to scout the place before the crime saw Matt Brannan and J.P. Mitchell openly carrying their firearms. You can listen to Mark Walters of USCCA's Armed American Radiointerview Matt Brannan and J.P. Mitchell for more details on the event. Over the years I have also heard multiple first hand accounts of possible criminals who seemed determined to commit a crime as they approached their potential victims, but suddenly turned away when they noticed a holstered firearm.
If you think about it from the point of view of the thugs it makes sense. Why would they want to attack a group of people where they know at least one person is armed for self defense when they can easily find another group of potential victims where all are likely unarmed? Why would they want to significantly increase the odds of being shot by one of their intended victims? Before you say it, yes, there are situations where a crazy person determined to attack a particular location would attack irregardless, shooting at the known armed people first, but that situation is rare relative to the typical crimes committed by criminals who are simply looking for an easy target.
If you do choose to Open Carry, I recommend that you utilize and train with a retention holster. I like the Blackhawk SERPA holsters as they hold your weapon securely, yet allow you to remove your weapon quickly & easily with a little practice. What is your favorite retention holster? Let me know in the comment section.
Learn more about Open Carry at OpenCarry.org.