Kauai is just about perfect - smooth, buttery, and minimal fallout. They almost feel like a cream. My problem is the intense metallic finish, not exactly work appropriate which means it would go to the back of my drawer and rarely get worn. For the price, my practical side just can't handle this.
China Seas is best described as just completely lacking pigment, different primers (including NARS Pro Prime) did not help much. You can tell how forced the swatches are below, it took multiple layers to get the color to that point. The only way I found that really made these stand out was to layer on top of NARS Soft Touch Shadow Pencils. So I had to first use Pro Prime Shadow Primer, then a Soft Touch Shadow Pencil blended in, then the eyeshadow on top. This method worked great and lasted all day for me, although it is a bit of a process that I don't have patience for at 6am when I'm getting ready for work! The second problem was that these colors really just did nothing for my skin tone. While the blue and berry look gorgeous and complex layered in the swatch, this effect was totally lost on my eyes. I could see it working better on other people, but my skin is just too warm for it to look flattering.
Bottom line, I will probably return both of these for the NARSissist palette. For almost the same price as two duos, I can have 15 different shades that I would wear on a daily basis. I did have fun creating a few different looks with these two duos though that I will post soon.
Swatches, layered then individual shades: