There is a 2.2.2 firmware floating around for the PTV3000. I can't comment on the Nexus 4 specifically, but it does work with the Galaxy S3 and the AllShare Cast app on it. I have had great performance with it, especially compared to the 2.1.5 that was just absolutely horrible. I would be interested to know what someone with a Nexus 4 and the 2.2.2 experienced as well.
Also, in the 2.2.2 update, it looks as tho the button on the side for switching between WiDi and Miracast isn't used for switching modes anymore and the device is always "listening" for both types of connections. The screen doesn't reference WiDi or Miracast now, just basically says"connect your device".
Thanks
2.2.2 is working with my Nexus 4. The stream is OK!