I'm no expert, but I was reading something interesting about this topic in Acoustic Guitar Magazine the other day. They said perhaps an instrument appears to sound better after time because the player knows exactly how to get specific tones out the instrument. For instance, where you strum in relation to the sound hole, how hard to strum, how soft to strum. So in essence, the instrument isn't really "opening up" as much as the player is just getting better at playing that specific instrument. The article said a test was conducted where two identical Martin Guitars from the 80's where set aside for this exact testing. One was played regularly and one was put in a case and never played. Then recently, they had several hundred people play both guitars (blind folded I believe) and the results were that neither guitar was obviously better sounding then the other. Some said the "never played Martin" was warmer sounding and some said the "regularly played Martin" was warmer. When I first got my Kanilea I strummed the thing way too hard because I was used to a Cordoba uke I had that required hard strumming to get volume. You don't need to pound on a Kanilea to get volume and in fact the thing will bark if you play it too hard. Thus I think it has warmed up but in actuality I think I just play it softer which produces a nicer tone. Of course some will argue against everything I just said. My two cents.