If the sections of terrain are all tesselated the same then surely you just need one index buffer for the lot?

The way I currently render terrain is to have multiple vertex buffers (well actually mutiple sections of the same vertex buffer) and use one index buffer to index every terrain section, priming and utilising the vertex cache wherever possible.

I still can''t understand how this whole ''transform the entire section of the vertex buffer'' can possibly work with the vertex cache. Anyone?