Aloha Mark,
I’ve made a number of different sized ukuleles using figured wood for the back, sides and soundboard. I’ve also measured the physical properties of tops made from other woods and koa as well. See enclosed figure. The tone can be ok, much like mahogany, but the wood is structurally weaker. And that means that you’ll have to make the top proportionately thicker. I usually ended up sealing the instrument bodies with epoxy as a pore filler, and with figured koa, the resin went all the way through the top!