Thanks efflux. I haven't tried it yet, but I believe you can mask erosion in World Machine -- seems like I remember a question on their forum about that a few days ago.
I agree and liked the stepped version better (actually a little of both, so maybe I will go back and lower the erosion power a bit and increase the terracing on the others.)
The last image was to illustrate the elevation center problem which is obvious in the terrain in the background. When they are close enough to overlap or objects, like rocks, it is less obvious.
One feature I use a lot in WM is the randomize. Once I get something I like, I save, randomize, save, etc. and have a group of similar terrains which I can throw into TG2 and see how they look with a real render.
I'm probably going to wait for my TG3 upgrade (four more days to go!) before getting serious with this. I'd like to make this my first TG3 project.