I'd like to mention one other reason why I believe open carry may not be a good idea, and of course it's my personal opinion only.
In the unfortunate event that we have to shoot a bad guy in self-defense, there's always the possibility that we'll end up in court. If it was not a clear cut case of self-defense, and therefore not clearly and obviously justified, we could be charged with a crime. Even if we're not charged with a crime, we may be sued in civil court by the bad guy, or the bad guy's surviving family. In either event, the opposing attorney is going to try and paint the shooter as a trigger-happy cowboy or a Rambo wannabe, who was just itching for the chance to shoot someone. Of course this isn't true for the vast majority of we law-abiding citizens who carry guns for personal protection, but that won't matter. Depending on the jurisdiction, this would be more likely to happen in a civil case, as opposed to a criminal trial, IMO.
Could open carry give the prosecutor or plaintiff's attorney some ammunition in this regard? I personally believe that it certainly could, so I'm not going to risk it.