It's just a guess but after handling thousands of sets of koa you get a knack for using visual clues as to what a fished instrument will sound like using that wood. After seeing Doc's latest pic of what #1 would look like under finish then I'm not so sure any more. In my experience, koa with black or very dark stripes like that shown in #2 can often be very dense and heavy, resulting in a tighter, less open sound. For me, color alone is often a good indicator with lighter color koa being lighter in weight. Physical inspection though is more important. (For best response, a good tone wood will be both stiff and light.) But we're talking about a very small degree of difference. I good builder should be able to build a good sounding uke with almost any koa but the approach and effort required to do so may be different.
Below is a good example of what I'm taking about. These two sets of koa couldn't be more different in their tonal qualities. I would much prefer to work with the koa on the left than that on the right. When ordering an uke though, most people are going to choose the koa with the most visual impact.
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