When I was in Guatemala, the cops walked around with semi-automatic rifles that looked like 'assault' weapons (cosmetically, black with pistol grips, etc). It just creates incredible unease, the atmoshpere is not comfortable, like always looking over your shoulder and walking on eggshells. I don't like it.
I especially wouldn't be comfortable on just some random person out shopping or whatever.
I'd be very nervous and quite possibly turn around and leave - especially if my kids were with me. I'm just not used to seeing people carry weapons like that. Police officers, yes. But I can't remember a time that I have seen an ordinary person carrying a visible weapon on them. I'm sure I've been around people who had it concealed and I had no clue. But visible - it just doesn't happen where I am. So yes, it would make me incredibly nervous.