Volume displacement (workaround ?)

I lately tryed to get volume displacement work in blender (cycles), but I had some issues. I used the pointdensity-node and a really dense mesh as source to get this effect done. But this has a view downsites :

• It's not an actual volume, its just the outer shell of it.
• It's quite limited in resolution.
• It's slow
• It's unstable

It would be helpful to have a node that is capable of checking if a certain possition in 3D-space is intersecting a specific object. This way one could check for the intersection in the volume shader and could thisway adjust the density. To get volume displacement work one would just have to distort the input possition in a certain way.