1) if a person has evil intent, nothing is going to stop them.
2) the whole 'first target' issue has happened twice in the last 10 years (by all reports) so I don't think it's an issue
3) I've actually watched open carry be a deterrence for some that had obvious ill intentions, so it does have advantages that concealed doesn't.
I've only had the pleasure of seeing it pique the interest of some city folks. Somewhere in Chicago there a pic of me with my squirrel pistol in its holster on my side in front of my dog box. Funny story. But I also realize that you and I frequent different areas with different obstacles.