Yes, for shelves there is not nearly as much stress across the grain as
the length...



toller wrote:
How does it outperform solid wood? Most solid hardwoods can handle loads
in excess of PLY?


Not cross grain

Yes ply is acceptable... absolutely.. but I don't know other than price
how it outperforms solid hardwood.



Stability


I like the spline and reglue idea,


Odd, I think it is terrible idea. I put a lot of work into matching to
avoid seeing glue lines, and he is creating them for no purpose. Well, each
to his own.



Sometimes the wood is not very intersting and breaking it up can help to
make it more interesting.... sometimes it can be disturbing..