Being able to insert channels into terrain rather than editing in 12D or other software would be more practical for smaller firms to turn around modelling ideas.
Landscape packages allow terrain meshes to be manipulated with tools that sink into mesh easily. Channels and swales need slope, not simply vertical depression to model correctly. XPStorm allows 1D modelling but this isn't useful for presentations and Civil 3d and 12d are catching up quickly now that rational method is being phased out.
