Laid in the final track for the outer loop and ran a number of locomotives and short trains across it for testing. Its looking pretty good! All the locomotives traversed the curves and the grades with no noticeable movement problems. At least none of them rolled off the tracks!
The homasote roadbed over the styrofoam risers is not as quiet as I'd hoped. I'll investigate other sound deadening options as I work on landscaping the layout.
The big surprise was testing the GP 35 on the outer loop and being startled as the Lackawanna 4-8-4 chugged by on the middle loop. Seems that connections and power transfer and excellent at the junction switches between the two loops. Now I'll have to bone up on wiring to insulate the two loops from each other.