Is there a difference in adding a fake stone shader to terrain rather than the shader tab?
I would think that if you add the stones to the terrain; and, if you have plans to use surface shader layers to the terrain - then, the surface layers would cover the stones.
I use this method often. It helps break up the terrain. Very large scale fake stones work well here. Then you can add further displacements and strata. If you have the strata before the fake stones, it helps break the coverage of the strata.