Hi all,
I've managed to implement a geo-clipmapping terrain for Babylon
It is based on the awesome writings of Florian Bösch (https://github.com/pyalot/webgl-lacr), and Jasmine Kent (who uses Florian's method and explains it nicely here:
In theory this kind of terrain is really good for WebGL, because it puts most of the work onto the GPU and it allows very large terrains.
My implementation isn't quite right at the moment though and I hit a few snags trying to implement it in Babylon:
1) Florian's implementation uses non-indexed meshes and triangles. I figured out how to create the same shapes needed using Babylon mesh functions, but I am sending waaaaay more data to the GPU than Florian does.
2) I also struggled with other issues like how to give the different meshes their own materials/settings without creating a lot of duplication.
3) I'm not sure I am using all the settings correctly... I'm finding it hard to get good looking results.
4) The mip levels really don't seem to be working properly
5) The detailing is definitely not right either 
I think I've come about as far with it as I can with my understanding of Babylon... but I am hoping some smart people in this community can help me fix it / finish it
Source code is at: https://github.com/darrylryan/BabylonTerrain