Whoops, actually I just realized that the phantom layout only has three columns on the numpad part, not four like the CM TK.
One thing that I like about the CM TK layout was that it has the arrows with the enter next to it, because often when you type into an entry field (like the location bar in a browser), it brings up a dropdown, then you have to arrow down to choose one, then push enter. So I like having the enter next to the arrows like on the TK.
Unfortunately my TK has older firmware with a bug where the enter key doesn't work if the arrows are active, but that's another story and I'm thinking about hardware modding it so the numpad enter just sends a normal return key. But that's another story.
Are there any other programmable TKL layout boards other than the Phantom and the GH60? Or boards where it's relatively simple to just connect the matrix outputs into your own controller, or fit a ps2 converter in the case?