Particle Board & Laminated Particle Board. - Model Railroader Magazine

Probably the coating on that particle board is melamine.  The problem(s) with particle board are its weight, the comparative difficulty of cutting it, drilling holes into it, nailing into it (very difficult), and its tendancy to break off chunks when under structural pressure. 

I have some long wall mounted bookshelves made of melamine coated particle board and they do show a sag between supports.   So do not expect the coating to do much to prevent that.

Uncoated particle board shelving in my garage shows signs of swelling where it has gotten wet over the years.

Cheap particle board bookshelves (assemble yourself kits sold at home improvement stores) of the kind often found in college dorm rooms tend to break off chunks where there is tension or compression.   They especially tend to break off when being picked up by an unsupported edge or end -- something to keep in mind for a modular transportable layout.

On the other hand tons of furniture, cabinets, and other constructions use the stuff so clearly the problems can be overcome.  If the stuff was free and you have a lot of it I would say, use it, or give it a try, but be prepared to have to deal with the problems and characteristics of the product.   Particularly the weight and the tendency to sag.

I don't know if the melamine or formica coating is a plus or a neutral for your purposes.   It may inhibit the swelling I have noted where particle board gets wet but it does not prevent sagging.

Dave Nelson