While not all layouts need to use  lift out sections, I felt it would be helpful:

1) the shed gets very cold in the winter, and I will be able to lift a section into the house and (subject to wife's approval) work on it on the kitchen table.
2) the main baseboard is 3 feet wide, and reaching the back would be a problem. Lifting the rear sections would help.
3) eventually I may be able to have several boards fitting into the same space, therefor changing the layout.

Obviously, the gaps between the sections are a concern, but with some accurate cleverness, I hope to minimise the unsightly gaps.

Here are some pictures of progress of the first section, which will contain an engine shed and an access road to the goods platforms.
 
I will have to update this page as I progress.