It would be great to be able to adds comps to already existing things or defs without editing that def. just like you have recipeUsers in recipedefs, it would be nice to have a compdef that has compUsers tag to allow adding comps to vanilla defs without breaking compatibility. Also it would be nice to be able to add comps to specific things that have been spawned into the game already, and have those things save/load those comps. This would allow for more variable and unique items as each things function could be changed independently through comps
+1 we need more "[blank]users" for big mods like SC. For example wood torch uses table def.
EDIT
And we also need a way to "remove" vanilla defs.