Not sure what you mean by "massive" really. The scale is often more determined by how you surface map something and/or what objects or other visual cues (e.g. atmospheric haze) you put in to imply scale. The terrains Martin and I have posted could easily be used at "massive" scale in TG, making for very large mountains, and would give a great impression of scale with appropriate atmospherics, plant populations, etc.
Now if it's the *shape* that's still a problem, that's another matter.
- Oshyan