I agree, I am underwhelmed about this design. I have been selling printers (http://www.alayax.com/3d-printers/av...inter-108.html ) with a similar bed size, with a proven design, for months, and he is not doing anything particularly innovative. He does have those six guide bearings, but only on one axis, they are going to dimple the Z-axis shaft in no time, and that is going to reduce the accuracy even more. Unless it prints really slowly.

It might be good for adding to an existing object though, maybe that is why he did it this way.