M,
I will never own another pool if it is not a saltwater pool... I love them...
Here is a story that I have shared before... I updated a rent house pool with new plaster, tile and flagstone coping like yours. At that time TFP was not even a glimmer in my eye, so it was a standard chlorine pool.. After a couple of years, you could see where thin layers of the coping were shedding off some of the flagstone. "Bad" stones and "Good" were right next to each other. I'd guess that about 40% of the stones had this shedding issue. A short while later, we upgrade to a saltwater system, which has been in place about 6 or 7 years now.. The "Good" stones are still good and the "Bad" stones are still bad. But, if anything the bad stones do not appear to be shedding as much as they once did..
The whole point of this story is to say that adding the salt system had zero effect on the flagstone erosion.
If I were building a new pool, and had to choose, between coping or saltwater, the saltwater would win every time, hands-down..
Thanks,
Jim R.