Hey,
first of all, very impressive work so far on ! 
I tried using it for landscape and even with renaming the sample (made a material function out of the complete thing) I did not get it to work. For some reason, the landscape just becomes invisible when I apply the material. So I am not sure what the problem is here.
I also did not get tiling to work. Tweaking texcoordinates only has an effect on the heightmap, but not on the diffuse in which it gets plugged later on. Shouldnt that just work?
Next question…
Is there a way to get it to work together with WorldAlignedNormal? It would be sooo badass to have a landscape material that supports the POM effect and projects textures in 3d space to not have stretching on steep slopes