A M686 is Stainless Steel and will never peel or flake since it is not a coated or have an applied finish. They simply finish the raw metal to a satin, soft looking finish. Sometimes through constant holster carry the finish may get a bit shinny where the holster makes contact with the metal, however I doubt you are buying this model to carry so it would more than likely be a non issue.
I have no scientific evidence and have not kept official records, but from what I have seen & heard here on the Forum, many of the Pro Series revolvers are not put together in a proper manner and many seem to have QC issues. One would think just the opposite since the revolver is getting extra care and refined for a specific use, however this is simply what I have noticed over the last 10-15 years.
If you can personally inspect and check one out, that would be key! If this is something you would be ordering or buying online, I'd not buy it without the specific right to return and not accept it upon careful inspection. I would check for barrel alignment, lock up, timing, barrel/cylinder gap, fit and finish, yoke alignment, general function and action smoothness, and of course general overall quality. While a purchaser of a brand new gun should not have to worry about all of this, it's just the way things are now.
Personally, I'd opt for a standard model 686 and not a Pro Series as they seem to have less issues, higher QC and shoot quite well. Again, no scientific records kept, just my general consensus from being here for many years and reading many complaints about Pro Series guns. Good luck with your purchase however you proceed.
