All good points D and Foo.
I think that 9mm is an acceptable amount. Perfect? Nope. But for $15,000, I can certainly live with it. I would rather have a watch that is 37mm, with a smaller movement, than a watch that is 34mm with a perfectly sized movement, all else being equal. I thought the movement in the Traditionelle Small Seconds was on the smaller side of things, but it certainly did not bother me.