The Z1 mixer by NI is great! It really is, and with the X1 you have so much control over Traktor with a nice compact controllers.
You can really tell a lot of thought went in to these things, and that just lets you wonder, why the mode button is so useless... why not make it like a shift button, with more functionality?
Now that's not such a big deal, so besides that everything is great. I highly recommend anyone who's thinking into getting in to this to buy it.
If you're not getting into DJ'ing, and just want a more compact set up, well get two X1's and a Z2. Honestly losing the jog wheels is awesome.