Chas-
I love the idea! Congrats for coming up with something so novel. I could easily see your concept being exploited to grow other fruit trees. I can envision the planting of multiple trees like the spokes of a wheel, and making a circular, espalier garden. You'll just stand in between the "spokes" when harvesting the figs/fruit.
Space saving, compact design, with high yield potential. Great for small urban pocket-gardens, small spaces, as a special feature in larger areas, etc. Once the initial set-up and planting is done, it should be easy to maintain, water, and the trees can be easily trained.
You could also make the chicken-wire central rooting area more permanent, and use stackable, interlocking, retaining wall, concrete blocks as a substitute. When stacking, you could leave out some of the blocks so that the trunks of the planted trees can extend radially, outside the block structure. Just substitute concrete blocks/bricks/stones for the cylinder shown in your diagram in post #1. (Fig trees planted using this idea will have to be considered as in-ground trees, and will need some protection in colder areas).
Thanks for sharing this idea. With threads like this, who needs to buy books?
Frank
EDIT: I assume that you have devised this concept to be used as a permanent planting system, and my above comments were made with reference to a permanent planting. I also assume that when the trees are laid and planted sideways, they will be unpotted.