I just discovered this thread "by accident" and I'm so glad I did.
This looks amazing, I love in particular that it can be used with traditional keycap sets while maintaining the compatibility with traditional Ergodox keys too.
Also the design looks really great, I love it.
I know this is probably super-late so it will most probably not make it to the GB, but I would however recommend that you find some way to let us tent the split halves: tenting is a big deal on this kind of board designs, and it's the only real thing this board misses to be perfect.
It's not necessary to think of something too fancy: simply adding support for the Ergodox-EZ tenting kit
like the Iris case does would be perfect in my opinion, but also just some screw-holes I believe could be enough.
Great project nonetheless! It's great to see innovation being brought to these ergo layouts.