There's a post I made earlier this year about this, which includes some movies.
I know it's not an open protocol but the details of it are unpublished at the moment. The PCIe capture card implements a Xylinx FPGA that replaces completely the USB connection between the host and camera. The SFP+ modules that shipped with my sample were, surprisingly, 10GBASE-IR 1310nm (blue banded), so 2km range single mode signalling. They're unbranded, and I haven't yet read their EEPROM info to get the manufacturing codes because the host I use in my house for 10Gb NIC driver testing for $DAYJOB has all its ports filled with $DAYJOB-related stuff at the moment. I do want to test DAC connections with this, though. I just need to get some DAC cables that are long enough for my office setup and the peecee that the PCIe card is sitting in at the moment.
Commands from the host are multiplexed over the 2x 10Gb connections and frame data and camera telemetry is received the same way. In its current state, both connections must be present (you can't run with just 1, but then again why would you.) QHY does want to get the on-board FPGA running with an IP stack and be able to talk over a UDP-based protocol which would obviate the need for the PCIe frame grabber and allow use of generic 10Gb NICs (Intel X520, X550, Myrinet, etc). They're working on that in the background amongst their other projects.
The frame rates over the existing PCIe frame grabber is very consistent when running the camera via SharpCap, which runs the camera in stream mode. 4fps for full 16bit resolution with an early version of the QHY SDK in pace. This is 480MB/s of frame data, or just under 4Gb/s of data that the camera is pushing out. While this doesn't get close to filling the 2x10Gb/s pipes, It would seem that the bottleneck is the FPGA or the host CPU. At any rate, 5fps at full resolution is pretty mighty and you would still need backing storage that would be able to ingest that data rate. FPS increases in a predictable manner as one specifies smaller ROIs on the sensor.