I have owned a few Kamaka white label sopranos and they are cool historically, but for me, the sound was not there compared to the new. I also owned a fabulous Kamaka HF-38 lili'u that looked gorgeous but was a bit difficult for me to play. I decided to sell and find an HF-3 to replace it. I got a 2003 HF-3 and it is so much easier to play, the sound is wonderful and I love it. I recently compared the 2003 with a 2019 and I did not see, hear, or feel any difference. In the case of kamaka- I like the newer, but 2003 sounds the same as 2019.
For KoAloha, I have an early 1997 soprano without the unibracing and musubi soundhole. It still rings like a KoAloha but plays more like a Kamaka. It does not quite have that KoAloha sound, but still a quality ukulele that easily outshines most others on the market. The addition of the unibracing makes a difference. I had a 2012 KoAloha Tenor that I absolutely loved. I traded it for the Kamaka tenor mentioned above. Last week I got a new 2019 KoAloha tenor, and although beautiful to look at and lovely sounding, the one I traded had just a tiny little more of that KoAloha boom sound that I love. The difference is miniscule but i could tell. it may have something to do with the different finishes on the ukes, but basically, they are the same uke with only the finish as a difference. Volume wise, sustain, clarity, and playability are just about the same. Also, it could just be that different instruments have different voices. Both tenors are definiately KoAloha in appearance and sound and my best ukuleles.
I have a 1940's and 1968 Martin Tenors. Both are basically the same but when you really nit-pick, the 1940's has a tone that I like a little better. Same volume but the tone is not as bright as the 1968. I like the deeper tones. Both are great ukuleles, but the tone is different. The 1940's is a bit deeper. I have not found any of the newer Martin's that I have played compare comparably to these older versions - they just don't. The 1920's Martin soprano that I have sounds like no other current Martin soprano that I have played. The tone of the vintage suggests to me that with Martin, as opposed to Kamaka, the vintage is preferable to own.