Very interesting as "Histoire du 1er régiment de cuirassiers" Author: ???, Publisher: Lachèse et Dolbeau (Angers), 1889 link has (my rough translation):
17 September 1802, the First Consul prescribed to Berthier, Minister of War, to prepare a project to reduce to 18, the number of regiments of cavalry, and arm the first five with cuirasses, which with the 8th gave 6 with cuirasses. The first four regiments only were ironclad.
Will see what the other regimental histories (if accessible) have to say – certainly "Histoire de la cavalerie francaise" by General Susane makes no mention of Yves Martin comment.
"Histoire du 2e Régiment de Cuirassiers, ancien Royal de Cavalerie: 1635-1876" Author: Antoine Ernest Rothwiller, Publiusher; Plon, 1877" link makes no mention of cuirass until the 1802 reorganisation..
"Histoire du 3e régiment de Cuirassiers ci-devant du Commissaire général: 1645 – 1892", Author: Charles Maumené, Publisher: Boussod, Valadon et cie, 1893 link makes no mention of cuirass until the 1802 reorganisation.
Again "Histoire du 4e Régiment de Cuirassiers, 1643-1897, Volume 1" A. Lahure, 1897 link makes no mention of cuirass until the 1802 reorganisation.
Have also now looked at "La cavalerie pendant la Révolution" by Édouard Desbrière – again no mention of cuirasses other than the 8th.
In the light of the above has Yves footnoted his comment, and if so what does it say?