I am going through the opposite. I got my ZS5's first, followed by the EMI CI880 and the Urbanfun last. I keep going back and forth between these three, but so far, I think the Urbanfun is underrrated, at least on my setup, which is also a Nexus 6p. I am running Flash kernel with EX Kernel Manager on mine, so I am boosting the volume by 8dB. I also use the Ainur Audio stuff to basically just feed everything through the DAC without messing with it. I also use Neutron music player, without the EQ so far, and I am very happy with the output. It plays all of these iems as loud as I would ever care to listen to them.
But, of the three iems, the ZS5s and the Urbanfuns are close. The Urbanfuns have better soundstaging than some here give them credit for. So far, the basic difference is that their low end is a touch better, and female vocals are not quite as recessed as the ZS5. These are both good qualities for me. Today, I listened to Prisoner, by the Jezabels, an Aussie Indy group. For me, the Urbanfun was my favorite on this. For classical, I think the ZS5 is edging it out a bit still...
Keep in mind, this is my source, my ears, and my sound preference, so as always, YMMV!