Primary Machine cerakoted the slides on my P07 and P09 (also milled the slides for the RMRs, installed the RMRs, milled for the rear back up sight and installed the front/rear sights) over 18 months ago.
My P07 goes in/out of a kydex holster (not finish friendly compared to a soft nylon/leather lined holster) almost daily. I think it was about 2 months ago that I finally noticed the first sign of wear on the front corner (on one side) of the slide.
I try to keep the metal parts wiped down with an oily cloth after cleaning/lubing (yup, I wipe and oily rag over the cerakote every time as I make sure I get oil on the sights, the pins, etc.) and so far I've seen no rust. In the summer time I sweat enough that after 2 or 3 hours in a holster the pistol comes out looking like I left it out in the rain with all the moisture beaded up on the surface. I don't have a show gun, they are "working" guns and are on my hip even when I'm up under the car/truck changing oil/oil filter or working on the brakes, rolling around in the grass while playing wit the dogs, etc.
Good luck, with whatever finish you choose.