If my memory serves me correctly, this was a California juniper that several of us at Boon's Intensive wired on in June of 2005. These trees are always a puzzle to wire well, and a real challenge and learning experience.
From such a distance, it does look like a shimpaku. Californias tighten up quite well, from what I can see at Boon's. This tree was exhibited in the 2003 World Bonsai Contest. (Note: it's not the same tree).
With yamadori, the chanllenge to wire is technical. Of course styling the tree is an artistic pursuit, but putting wire on well is an art in and of itself. Figuring out where to route your wires, how to use just enough and avoid crossing wires, etc. There are challenges on these branches that you won't find on a fairly well-groomed tree.
This is a close-up of a portion I had to wire. This was about my third Intensive.
Yamadori tend to sway from the groomed trees in the structure / branching rules, we are using wild grown trees for thier age, deformaties, stunted(ness), in general rugged appearance. It's kind of a trade off between the naturalistic ruggedness, and the typical artfull styling.
Throw on top of that the age of many yamadori trees often makes bending some branches impossible or risky at the best ( can you say snap). Often a small branch on old stunted juni's could have been set in place for many years, and won't move easily.