Reply to "Prewar Marx 0-27 Compatible with Lionel 0-27 Track"

Question about Marx 0-27 and Lionel 0-27:  when I was a kid you could only find Marx in stores around this time of year, so I bought Lionel 0-27, found year around in hobby shops,  to expand my layout, with no notice of any dfference.  As for wider radius, Marx did make and include in some sets 0-34, which made possible parallel curves/double track loops.  All of these are interchangeable, except, of course for the curve radius you want.