Love to see the evolution of this plan Ken. One other operating option that could be nice is to let a train run from the top reverse loop up the hill to the 045 loop and back down. It would require adding a switch from the ground level loop to get back to the outer track to the top again.
I think the small industrial sidings may need to be sacrificed or at least modified to fit the extra switch to make the reverse work but it could be an interesting option.
A 12 X 12 plan that can handle 4 trains at once is a lot of action for the size of the layout.