I even made a post about it ( in fact, a post about the 5140, another one about the 5177, and the last one ref to the Tradition ).
The 5140, enamel or not, is another expression of Breguet tradtion ( enamel, or guillochage ).
The Tradition is well called, indeed, as it enhances the " Pare Chute ", and is looking like the old Breguet watches.
If I had to choose, I would go on the Tradition.
If you do a search, " And the winner is ", you will find the post.
Hope this will help you,
Best,
Nicolas