Some PROs to start:
- lightweight
- easily carvable - both for irregular edges or curves to the train board, and to create slopes - either steep or gradual
- helpful with sound absorbtion
- low cost
- strong enough to bridge 16" centers without sagging sufficient for train and scenery weight
- easily stackable to build heights and mountains, and carve-able for ravines and canyons
- accepts latex paint and glue OK
- can be screwed using Gorilla glue (an expanding foam glue) to build a strong screw socket, or combined with drywall screw anchors with glue (I have done this myself for Fastrack, and the screws can be removed to reposition the track)
- Has been shown can be shaped and cut with minimal "dust"
- does not block wifi signals, is insulating
- a small slot can be carved in the surface using a knife, to push wires into, which can be then be run near the train-board surface without under-table wiring
- easy to drill, or no-drill with an ice-pick or nail for running wires through the foam board
- can be combined with other scenery techniques
- can be used with expanding spray foam to build and fill terrain and hills
CONs:
- not as strong as wood or other materials
- some have mentioned a fire risk: creates noxious combustion fumes
