The Z-cam has 4k 120p that is pretty darn solid as well as the option for electronic ND's and internal Prores HQ 422 at full resolution.
This has built in SDI which is cool but you can't external record through the SDI so that is a bummer. At least you should be able to get a feed to an external monitor that doesn't have horrendous latency. Is the HDMI implementation here faster though? If it is that would be a big advantage. The HDMI out on both the S1H and Z-cam is very slow.
Internal ND's would have made this camera a huge win, without them its kind of meh. The only advantage of the lighter weight is for drone use. Once you add a monitor you lose the weight advantage.
The new Nikon camera will have internal prores RAW. If this had internal RAW and in combination with the SDI out I would buy it.