I'm just coming back to this after some time writing drivers! However, I'm still having trouble getting this XStick configured correctly and paired with HE, would you mind giving me some pointers, @simon - or anybody who, unlike me, knows what they're doing! 
So, trying this on Windows 10 now, XCTU up and running, legacy drivers downloaded. Firmware 23A7, ZigBee Router API, PAN ID set, JV set to 1, rest of the settings match your screenshots. Should I then continue with adding the micro python code described in the first post of Everything XBee or is that not necessary? I just receive the message:
Could not access the XBee file system. Make sure your XBee module supports the file system feature and the serial port parameters are correct.
I've got no idea if the XStick supports this or not!
So, I continue on without uploading the micro python code and presumably I click the tiny "Discover radio nodes in the same network" button with HE in pairing mode? Well, though XCTU says "Waiting for remote devices to answer..." I see nothing on either side. 
