David,
Glad to be able to provide some information, and you are right RR is awesome but pricey.
The American models locos are great, and I have two steam, and three diesels from Lionel American flyer, I just stay with high rail for my use.
Since your post starts with Polar Express, I have to say the Lionel American Flyer S gauge set is not a scale unit, but is a great train, at a very god price point. Check out the you tube video below, if you have not seen it already:
https://www.youtube.com/watch?v=OsSlYqH3mac
Aflyer