I have one gun that has cerakote on it, a Browning X bolt hells canyon speed. The cerakote will chip where metal on metal contact occurs with force, like where the bolt handle hits the receiver when you lift the bolt. It hasn’t spread at all. I like it, it adds a layer of protection, plus customization of colour if one chooses. I will say that it does not instill the same level of weather imperviousness confidence that stainless does. Not that stainless won’t rust, it’s just thy Vera kite is only on the outside of the parts. Inside the barrel, receiver, etc is still just blues steel.
Also, I have never had a blued rifle rust on me. I always wipe them down with rem oil after ever outing, never an issue.