Anybody ever tried 3D Coat? It's a sculpting program, like ZBrush and Mudbox, except it uses Voxels instead of polygons. The advantage of that is that the sculpts are free of all topological constraints. You do not have to worry about edge flow AT ALL until you're finished. When you have something that is ready to be converted to polygons, there are really cool manual and AUTOMATIC retopology tools. Seriously, the thing is capable of doing all the work for you. Usuaually there are some symmetry errors in the result, but those are easily fixed in a 3D application.
So, if I were going to make terrain, I would go straight into 3D Coat and start sculpting. There's no real reason to do work in a polygon modeling application first. Then I'd autoretopo, export the polygon result, open it in my modeling application of choice, optimize the terrain mesh to a suitable degree. And done.
To be clear, I haven't actually tried this, nor have I messed with terrain in many years, but that's how I'd go about tackling it.
Bookmarks