Usually I've seen a single stripe of decorative purfling, but I ran into a problem whereby the black/white/black striping I had was slightly different than the one pre-glued onto my maple binding, and would look asymmetrical if I use them on opposite sides of the maple strip. My remedy was to use two maple strips with my smaller one in the middle. Ultimately I was very happy with this decision--the maple stripe has more presence now so I think it will look cool in the end.
I didn't take too many pictures of the back bracing process. It's similar in terms of arching and carving, except the patterning is different. I followed the book's spacing and used a 'Ladder Bracing' pattern. The rounded strips of wood between the 4 main braces are cross-grain grafts used to strengthen the back seam. By the way, the wooden cam clamps shown in the picture below are essential I've found, and completely worth their nominal cost. Here are the braces being glued in place:
Here is a picture of the final braced back after carving:
Here are the two plates and their respective bracing, side by side: