Hi, Both pink foam and Homasote will last longer than you will have your layout. Generally, you should homasote anyplace where you will need strength. This includes under yards and track. It is common that most layouts have places where you you need to step on them or place weight. Homasote backed with wood will not bend. Note that homasote is not self supporting and must be supported by plywood or other material.
Pink foam, on the other hand, will easily dent when you place a weight on it or try to stand on it. Don't use pink foam anyplace where you may need place any kind of weight on it. Pink foam is perfect for mountains and other kinds of scenery bases. It carves much easier than homasote.
Joe
