I decided to remove Raw sienna and add Quinocridone sienna. It makes outstanding oranges when mixed with Quin gold deep, and also a nice transparent deep brown when mixed with Cobalt blue. Quin sienna is very versatile. It's also powerful in intensity. Since I can create fairly decent deep values with colbalt blue and Quin sienna, I removed Lunar black.
Here are additional studies with colors I'm considering: Hansa yellow, Anthraquinoid Scarlet, Pyrrol orange, Quin sienna, quin gold deep and Cobalt violet. Some interesting mixes.
I decided to add cobalt violet because I just can't live without a violet in my palette. So for now I've settled on Hansa yellow, Quin red, Pyrrol orange, Cobalt blue, Cobalt teal, Cobalt violet deep, Quin sienna, Diopside genuine and Quin gold deep.
Here's a neat trick!
I found this brilliant trick (somewhere on flickr) for attaching pans to the tin using self sticking magnets on the bottom of the pans. So I bought a roll of magnetic tape and cut pieces to size. It comes in sheets too. At first I was skeptical they'd be strong enough to hold, but they do. Works great! Makes colors interchangeable with a click. No sticky stuff to deal with.