This is basically the selling point for me over the SL 4...

So my rig has a 2 turntables, and a DN-HD2500 below an awful 19" mixer, and I don't know how I would run my deck setup as my CF assigns suck, but I want to be able to assign the input to the HD2500's Left or Right control surface to any one of the 4 decks; and it has to be as a native controller, it feels really weird using timecode. I would also really like green and orange boxes around the deck (preferably blinking in unison with the controller's LEDs when no track is loaded) but now I'm just being picky.

So there it is: Native Controllers should be selectable as inputs for any virtual deck.
With a little MIDI trickery you could roll out 4 tracks with A SINGLE CDJ-2000!!!