I have a theory..
I'm absolutely in love with curly Koa, it's the most amazing thing to me.
However, in my experience, very curly Koa can sound a little dead. (Please don't take offense, owners of these instruments. I'm not bashing curly wood. Like I said, I LOVE it. And it can produce an absolutely gorgeous sound as well. It's just that the wood doesn't seem to resonate like a very nice straight grained wood.)
Like I said at the start of this thread, I have never seen a Koaloha that's made of curly koa, but I've also never played a koaloha that didn't have an absolutely superb, sizzling top end and vibrant mids and lows and incredibly long sustain.
My theory is that Koaloha knows that the best sound is to be found in that straight grain koa that they use, and that's a big part of why they're so consistently high quality.