Just a short info: I started working on this device.
The known Xirrus exploit works, so I have full shell access on the stock firmware and I can interact with the boot loader. I compiled a quick image a few days ago, but it fails to pass validation of the boot loader. I'm currently investigating why my image is not accepted.
EDIT: OK, i can boot images now - I should really read up on how to properly use netcat.
EDIT: I noticed that I did not receive the device mentioned above. While it looks the same from the casing, it's actually a WAP9122 with a CN7020 CPU instead of a CN5020 CPU. The board is very similar, just a few moved parts. Could explain why it's more troublesome to get working than expected.