------------------------------------------UPDATE------------------------------------------------
Uke arrived Friday in excellent condition, it even stayed in tune. I love Ko'olau's new case, black tolex with an arched top. Anyway, the combination I requested (ulawood top, koa back and sides) gives the best of both, and not the worst of either. The tone is still light and airy, but a little more centered and mellow. I get just a touch more legato than with the all ulawood, and a touch more dynamic range. It's quiet until you lean into it and then it can really bark. I think it's my best instrument as far as overall quality, the sound has a little more character than plain ulawood. But I still might pick the all ulawood for its added delicacy - I'm not sure yet.
One thing I've pretty much found, other top woods are not for me. Mahogany is too mellow and a little ugly on the high end, koa is too sharp and produces some nasty undertones, spruce or cedar I'm not as familiar with but haven't liked any I've heard. The ulawood seems like the perfect mix of characteristics. Of course, I am not playing live or doing much strumming, these are for melodic styles where the sound of plucked notes is what you hear, and what I want is a classical, almost Renaissance sound, as opposed to Hawaiian or pop. Mahogany or koa have more punch for those styles.
Ko'olau might be the best bang for the buck considering everything, even though you might not think so. The grade of koa I got is higher than the other K-brands I have. There's the shimmering "curly" waves throughout that you can't see in the pictures. You get a 17 fret fingerboard, only Kanilea does that right off the bat. And they come with a good case which, amazingly, no other K-brand does. So that saves you $140 right there. But of course the main thing is the sound and playability, it's a big step up, even on the cheaper models. Bravo!