Having recently relocated from MI, I will say that I never saw anyone OC, even tho the state constitution says you can. I was tempted a time or 2, but their definition of concealed carry makes it such a PITA that it would be very easy to get busted for CC. If your coat/jacket covers your firearm, it is now concealed. If you get into your vehicle with it in the holster, it is now concealed. If you have a CCW, you are fine in those cases. If not, you might get some unwanted attention. The traveling requirements are onerous as well. You have to keep the firearm and ammo seperate and inaccessible to the occupants of the passenger compartment (to the extent possible - single cab/seat pickups, for example, make this difficult to quantify).
That said, there are some open carry minded folks on this board if you go to the MI section. They get together and OC and have had no troubles the last time I checked in. Of course, metro Detroit wouldn't be my first choice of places to try OCing! Most places have passed unconstitutional laws that say you can't OC. If you got arrested, I would like to think that you would be acquitted. I didn't try it where I lived due to being the sole provider for my family. In theory, the law should be on your side, but what about when you get into the court room?
As far as a definitive answer, there is none. Even the state lawmakers have disagreed with the State AG's opinion about OC.