This looks like a pretty good tool, although currently I see nothing that justifies its existence. In case I'm wrong I'd really like to be corrected, but doesn't MED already allow you to easily modify terrain and create blend maps?

Regardless, in my honest opinion heightmap terrains are really boring anyway. They were interesting a decade or two ago when people first began putting them in video games but now whenever I see one I can only think of its limitations. Generally speaking, every heightmap terrain looks the same to me, and I can never be very immersed in a video game whose defining terrain feature is endless rolling hills.

This is entering the realm of a tangent, but Rage was graphically appealing to me not just because of the consistent 60 FPS and its unique texturing system but also because it never resorted to using heightmaps to define its geometry anywhere in the world.