i believe that is related to midi protocol and it takes literally less then 5 seconds to "rescan MIDI".
it is not like you have to do it 10 times per day. for me is not a problem, but small inconvenience.
i think that setup X1 and Z1 is probably more complete, but it is also more bulky and more expensive. And you can not use it for 3-4 decks Traktor equipment is not using midi by default that's why it works different and simpler, but you can not configure it as you want in this mode.
i prefer mine Xone K2 that i use with Traktor Audio 2 soundcard when i travel far, when i can i prefer much more Traktor s4
I agree with both
X1&Z1 = simple and easy
takes more space, more expensive than one Xone K2 and still just 2 track...
personally i use the X1 & Z1 setup at home and i would prefer the Xone for gigs!
'rescan MIDI' is indeed a 5 sec job and you are set!
still looking for a plug & play 4 track solution though
S4 is getting old, S5 too expensive and i don't know if it will work as well with 'ggrr' yosemite