I could imagine music in Ryzom playing similar to Minecraft. They are started and stopped by random and tuned in very subtle. I believe this could work very well. It should not be like the capital themes, which start upon entering that area. It should be mysterious and not predictable as in "this is Kipee Hill, where the Marching Kipee tune always plays." To me the sounds of the world and mobs always had a special appeal. I don't want to see it lost.
Just my 2 cents.
Just my 2 cents.