Pete,
Very nice looking layout and full of possibilities for operation and constant running. However, you have two reverse loops in the plan. If you are used to 3-rail, it would present no problems. But 2-rail means that you will have to provide for polarity switch at those reverse loops where the polarity of the rails is reversed. Not a problem that's insurmountable, just be aware that you will have to take that into consideration when wiring. Look into it.