It depends on how into these sites you are. We really do love them. Chauvet is a wonderful recreation. If you saw the film shot in Chauvet Cave of Forgotten Dreams, then you know what a thrill it is to see these wonderful drawings. For me Chauvet was a must and the area of the Ardeche is so spectacular. I think the drive along the river is one of the prettiest in France. When I visited I had my arm in a cast to my shoulder and so could not canoe on the river -- but it looked so wonderful -- canoeing or kayaking under the arch that marks the location of the cave.
It is most similar to the Lascaux recreation. It was worth it to me, but it is quite a trek to get there and not at all near the others, so I'd want to use it as an occasion to also enjoy the river and the area.
I got photo placemats at the gift shop at Chauvet and so enjoy those pre-historic drawing often.
Short answer: it was worth it to me, but YMMV