It seems that the game engine stops to render anything beyond a certain distance, one can recognize this effect in very large worldpaces:
http://img69.imageshack.us/img69/5417/distp.png
When moving the viewing direction, parts of the landscape start to disappear... and always the parts directly in front of the player. Its btw. not the effect of disappearing complete quads, this can be changed with uGridDistantCount.

This can be better explained by adding a virtual box which is rotating with the players camera direction (I guess in reality the GPU is rotating all the coordinates of the triangles). If one looks in forward direction, the triangles are outside of the box, by rotating the camera the triangles are rotated into the box.

I find this effect always very annoying. Its not the problem that the LOD has a maximum, the problem is that it is damatically visible when looking up/down or changing camera direction.

The question is: is this a hard coded maximum range, or is it possible to increase this range (the GPU is not yet at the limit, so it could handle more)?