Two of my French randonneur friends have indeed completed all diagonales. They have wonderful stories to tell.
I have an Ideale "Diagonale" saddle on my 1985 Singer camping bike, "rodée selon D. Rebour." It is a very comfortable saddle. Of course, everybody in France seems to have a preference in saddles - Brooks lovers and Ideale lovers don't seem to see eye to eye there!
Jan Heine, Seattle