I've been playing around with the displacement lister today for the first time.
First thing, it seems quite buggy. If I rename one of the materials that has displacement while the lister is open, it seems to crash. Also if I open the lister, close it, then rename a material and re-open the lister. This is happening in a very heavy file though, so might be hard to replicate.
Second thing; it's a bit strange that displacement has an on/off toggle in the lister, but not in the material settings? Is there not a way to turn off a displacement on a material any other way than the lister? Edit: Ah, I see it's toggle is in the maps list at the bottom of the material properties. Maybe this should also be in the displacement settings area of the material?