A full-on custom board has crossed my mind. I just don't have the capacity to add another project to my schedule now.
There are a bunch of things that could be improved on the current designs, between GH60, clueboard and banana split. For example, I would separate the PCB into two parts, one for mechanical functionality like switch mounting and usb port mounting and another for the controller. This would add to the cost somewhat, but then allow more flexibility if you want to swap the brains for a bluetooth chip or if you want to re-use a controller board on a new switch board, or if there is mechanical damage to the switch board, then the controller is easily salvageable, etc.
Another thing is layer indication, I believe some of the Ducky boards have this where first 3 layers have dedicated LEDs. I suppose this can be accomplished with underglow, but i don't want a disco show on my office desk.