Is concrete demonstrably a better material? It may require less maintenance going forwards but it’s much heavier than traditional roofing materials. Our house was tiled in concrete some 25 years ago and the roof had to be further supported by a host of trusses in the roof space to the point where the space is unusable. We have some spare concrete tiles. If you drop them they shatter into large shards.
As soon as I can afford it, I’ll be having the roof remade (not just retiled) as all that weight of concrete has been a disaster for our roof. Now, one row of coping stones is not going to weigh down your whole roof, but the building industry has form on this sort of thing, pushing materials that are easy in the short term , and I personally wouldn’t risk it. Maybe seek out the opinion of another roofer or two, if you haven’t already.