55 year old Fontainbleau local and traverse master Jean-Pierre Bouvier has made the first ascent of Fou rire aller/retour for which he suggests 9A trav.
The left-to-right is an 8B trav. in its own right, while the right-to-left weighs in at a mighty 8C trav. Adding the two makes a 9A apparently.
While traversing back and forth, up and down etc may sound odd to some, it's something that's been done for a long time in Fontainebleau and that's considered perfectly acceptable.
J-P has been a climbing for 40 years and has made the first ascent of a huge number of hard traverses. Before this, his most difficult one was Le Voyage de Zhong Kui en aller-retour, 8C+/9A trav., which he put up last year.
As far as I know, the only other 9A traverse is Hanspeter Bodmer's extension of Fred Nicole's E la nave va at Lindental, Switzerland.
A 9A traverse is of course ridiculously difficult, but shouldn't be confused with a 9A boulder problem (9A bloc), which would be almost impossibly difficult.