Offizieller Kommentar
I haven't personally had a chance to test this unit to do a comparison, and sadly, looking at the spec sheets don't really tell the whole story either.
Given the price point and positioning, I'm hoping that it comes in on par with the DJM-750/850 level mixer for audio quality, but as you said yourself - even testing with some mid-level speakers won't always show the weaknesses!
The phono inputs on the DDJs have been tailored to suit DVS signals, which is not as appealing for those wanting to play regular vinyl records, but again, not having used the XZ myself, I can't say what kind of component is in use or how it compares. Once I get one, I'll be sure to provide my opinion and comparison.