Comparing the older and newer versions of the layout design, the major change that enables other positive changes, is the connection on the LEFT inside loop that makes a return loop. In the newer version, the connection goes through and uses a portion of the RIGHT inner loop.
Earlier, I resisted this alignment, as it requires that a perimeter running train interfere with a train on the inner RIGHT loop in order to run the return loop connection around the LEFT inner loop. That is a negative aspect: running the return loop connection involves the outside perimeter AND BOTH the RIGHT and LEFT inner loops.
So why make the reverse loop connection in this "all-consuming" alignment? The first advantage is that the RIGHT inner loop is longer (better with a slightly longer run). And second, the added length allows the cross-overs to be constructed with much smoother O72 curves and the O72 'Y', a big plus. And third, the revised RIGHT inner loop now has better opportunities for spur alignments, including even a small yard. Fourth, I was able to make the FasTrack section joints at a closer tolerance - important as FasTrack has zero flexibility with compression due to its rigid plastic roadbed, and joints can be stretched only a small amount. I started the new version with a complete restart from zero, to make sure I had all the joints and alignments as perfect as possible.
So its a tradeoff: a convoluted return loop run involving (and perhaps stopping) trains on both inner loops VS the advantages just mentioned. Which way do you think is a better way to make the reverse loop connection?