Z1000 Pro gives equal picture quality and audio quality for video to UHD2000, so unless you need the DAC in the UHD2000 then Z1000 Pro is certainly more cost effective. It has the same interface/remote as UHD2000 so for video it will be almost the same. I say almost because UHD2000 has more RAM, which will make it slightly faster, but not by much.
UHD2000 (and it's imminent successor UHD3000) are aimed at people wanting a media player with top end hi-fi quality audio. The hardware DAC (ESS9068 in UHD3000) allows playback of very high bitrate audio formats (MQA, XMOS DSD512/PCM768) via analogue XLR ports.