Not sure if this is something planned but not implemented, but it would be nice to see the player fade effect not just apply to opaque nmaterials, but normal translucent materials as well.
The galaxy orb (particularly the colored side) is basically opaque, and the colored side of the default ball is also basically opaque when two or more players are in the same location.
It also helps a lot in being able to tell which ball is actually yours at the start of a level.