Hello,
So, I revive this topic.
The time I passed, and now we have documentation on this board: https://www.ardusimple.com/rtk-ins-simplertk2b-f9r-hookup-guide/.
But until recently, we couldn’t use this board because in RTK it was limited to 20cm accuracy.
According to Ardusimple when I ask them, simplertk2b-f9r-accuracy - ArduSimple the recent firmware update allow to reach 2cm accuracy in RTK (under test by Ardusimple).
Advantage of this F9R board: F9R use an IMU to provide dead reckoning, allowing to keep RTK accuracy for a limited time when we loss correction or GPS signal.
Other adantage I see: computed attitude (yaw, pitch, roll) of the rover by the IMU is dirrectly available through UBX protocol: UBX-NAV-ATT. So perhap’s we could use this data as a replacement of our current sensors (BNO055, MMA) as an other alternativ to CMPS.
Perhaps we need to connect this board to a microcontroleur that read NMEA and UBX-NAV-ATT message, and send it to the appropiate format to AOG (like OGI for dual antenna) ?
Drawback : the price compare to the Ardusimple F9P 
What do do think ?
Math