Threaded rods to create frame/axis connection. Which improvements can be made and are they needed?
If I understand you correctly, compared to a Mendel RepRap you are using:


M8 threaded rod (the same kind of rod used in the Mendel RepRap frame)
roughly the same lengths of rod as in the Mendel, and
cross-braced with more diagonals than the Mendel design.


So I expect less vibration and the same print quality as a Mendel.

Rather than put one block of wood at each corner with holes drilled at a bunch of weird skewed angles,
the "1X2 split vertex" looks like it is a lot easier to construct.

I've heard several people claim that lots of threaded rods and associated corner connectors can be replaced with a few big sheets of wood in a 3D printer.
See Mendel90, RP9, SGBot, WolfStrap, etc.

Looks like a very educational project. Good luck.