There are few places that have the unrestricted open carry that you desire i.e with a state pre-emption.
The only ones I know of are Arizona (although I'm not sure of their municipal guidelines) and Vermont.
Vermont is a very small state so it's not a good comparison and we'll have to wait on Arizona since it's fairly new there.
In my opinion there is no proof one way or the other.
My objection to open carry has nothing to do with bloodbaths in the street, which are believe are highly unlikely.
Michael Brown
http://opencarry.org/opencarry.html
You can click on the legend in the lower right of the map to see what defines a gold star state.
The above displays a map of states with OC that is for all practical purposes unrestricted - there are 8. VA is pretty much like AZ and VT when it comes to OC. I'm actually surprised that NM and NV show as gold star OC states - go figure.
FWIW - though I do believe that unrestricted carry should be the law I am realistic enough to know that today's society simply will never go there without a great deal of change.
A good start would be doing exactly what was tried last year. Amending the SDA CCW law to say "concealed or unconcealed" thus permitting those who have been vetted by the state to choose the method of carry they prefer. Not a perfect solution but at least a start.
My point is that OC is a choice and one that seems not to have been and is not currently an issue in states where it is legal.
I'm still waiting for someone to clue me into what it is about us Okies that makes OC a non-starter here.