It looks very much like the other examples I've seen in books, including Casque Militaires Francais Du XX Siecle, by Roland Hennequin. That example is in a museum. However, in Paolo Marzetti's Elmetti there is one that could be this exact helmet, but says only "Private Collection"). Over the years I've bought a couple of helmets, which were in private collections and I think they are the exact helmets in the book. That said that one on Regimentals could be good.
What stands out to me is that this helmet is one of many that suggests that the European armies had been thinking about helmets in advance of World War I. I'm one that doesn't believe the soup bowl story. I'm sorry but I want to know why a French soldier would have a soup bowl and why it would fit his head so perfectly. I maintain that the skull cap was instead used as a bowl as it was terrible as a helmet.
But regardless I do like the look of the French helmet. I think it is legit, and hopefully if they haven't sold it the helmet will show up at SOS.