Very interesting discussion with lots of good information. Ever thought about why to use train detection of any type on a layout? In an article I wrote in 2008, I outlined six basic reasons for detection schemes and the benefits thereof.
1. Control panel location monitoring lights. No real operational advantage, but nice to watch and show visitors.
2. Accesory & signal activation. No need to cite reasons here. Probably the most widely used application of layout train detection.
3. Collision avoidance. Primarily useful at crossings where two trains might converge.
4. Derail prevention. Some track switches don't have this feature and it can be added with the approprite detection scheme.
5. Train control. The most complex application. With the proper schemes and circuits, you can have trains running themselves on the layout.
6. Hidden track visibilty. Actually a slight variation of reason 1. Keeps track of trains in areas of the layout where you can't see the trains.
Almost any form of detection if properly implemented will work to accomplish any of these layout functions.
