My preferred method is using a gradient to sort a grid of cloned objects at different resolutions.Then have the GeoModifier do the displacement on them all.
*This is super flexible and easy to set up.. The grid numbers define the area you want to cover. You can set it up with 2 planes and have them blend between low res and high res.
Checkout the basic Cloner setup in the attached file (requires Mograph)
Check out DEM Earth here..