Keychrons are fairly functional keyboards - most of the models should work decently.
I have heard of issues, things that customizers would notice. In terms of which way the housing is facing, case and typing angle, keycap binding on some models. Some issues with hotswap sockets coming loose.
But some models are better than others. I would recommend looking up what people think of the K8, especially on sites like this one, Keebtalk, and on reddit. And Discord, if possible. This will give you a much clearer picture.
From a functional standpoint, it should be entirely possible to put Gateron Blacks into a K8. Ink Blacks are actually quite good, and apparently don't need to be modded. So with Ink Blacks, you should get switches smoother than MX Black. It's a workable solution, in theory.