I have both a Spoiler and an Epic with koa tops. I can't compare them to Alembic basses with other top woods (that particular predicament will soon change, though) but here's my 2?.
On the Spoiler, with the one filter, I find myself keeping the filter wide open because otherwise all the sparkle just disappears, even with a fresh set of DR HiBeams. Love the way it sounds, but koa is definitely not the brightest sounding wood.
On the Epic, defretted, with the bass and treble EQ, uh well, I actually cut most of the treble. Of course it's set-neck versus the Spoiler's neck-through, and a filter is not a treble control, but I think koa is especially nice for fretless.
And obviously it just looks amazing!