I have a Ralph Bown guitar made in 1986 which is koa top, sides and back and built to be like a Martin 0028. It attracts favourable attention wherever it goes because of the sound quite as much as the appearance. In fact, sometimes it gets more attention than I do, and I'm convinced it has its own fan club. It's a dream to record with, as wherever you place the mics you get a different tone, so we can vary the sound on different songs.
No problem with cracks (so far in its life, at any rate). No problems at all, in fact, except that I have nightmares when I take it on plane journeys as I'm terrified something will happen to it and I'll have to find a different guitar I love it to pieces.