I´m here :D ,but I must admit that I´m not 100% sure what you are trying to get at in this thread ...
After Sigi´s binding failed him, he was looking for other options (as Fin already posted somewhere here).
Maybe the setup on the picture is used because of the different flex, but maybe it is just used this way to have a direct comparison ... hard to tell. There are also pictures where he uses the Sidewinders on both feet.
Sigi was using (heavily adapted) Atomic boots in Telluride, but if my memory serves me right, he was using Northwaves again for the Olympics.
And he seems to have tested and even built several plates in the off season.
Having a different setup for the front and back foot has been an issue for quite some time - hardboot/softboot mix, different dampeners for the bindings, different tongues in the boots, etc. Whatever feels "right" for you and helps you feel comfortable on the board.