I guess my question would be why you're thinking of selling the Collings to get a Kamaka.
To my ears, they have different sounds. Do you prefer the sound of the Kamaka?
They also feel different to play, IMO, which of course, you can't decide if you agree without being able to play both, of course. But, do you like the way the Collings feels to play, or are you not happy with that?
I have a preference between the 2 brands, (and I am a concert player), but that's not relevant, I don't think. I think that the important things to consider are what *you* are looking for, and which ukulele would be more likely to suit you based on that.
From Graham Greenbag
The one thing I’d add to that is that it’s advice that applies across the spectrum of Uke sales and purchases. If you can afford to then it’s really helpful to compare instruments side by side at your leisure, and then to decide what to keep and what, assuming you want to or need to, to sell.
I will agree with the "hit or miss" regarding Kamaka.