DDJ-RZ with CDJ 1000 MK3

What do you mean? You can plug the CDJ as a Line Source and it will work.

That. ^^

It won't work as a controller itself, but the RZ already does that (and handles up to 4ch) so really, the CDJ-1000 would just be used as an audio input for playing CDs then?

its was more a question of could the CDJ load tracks from the Rekordbox library when connected through the DDJ?

Yes and no... if the upcoming DVS support includes the DDJ-RZ, you could then run timecode CDs on the CDJ-1000's and have the RZ controlling the track loading, etc, and then manipulate the audio via the CDJ.

Thanks for the response. Do you have any idea when you'll know if the DDJ-RZ will include support for DVS

Not at this time, sorry.