UPDATE on 29/09/2016
Today I managed to test out the px4flow, using the older version of ArduCopter.
I have the full test, using various parameters settings, on video, but I won't bother uploading as it really is boring.
Although the camera is recognised and the images can be seen through Mission Planner and the EB2, ArduCopter failed to use the camera as a means of holding x,y axis.
During my tests in POSHOLD, the copter ignored the images which were sent through by the camera.
Of course, I already knew that sonar (rangefinder), does not work with the EB2 and this proved to be the case.
During my tests, it was as if the PX4Flow was not even installed.
Don't waste your money on the PX4Flow, unless you willing to spend time writing your own custom code. This may work...but it may not.
From what I have been told, the LidarLite is the component which should work with AC, but due to lack of availability, I am unable to test this.
I have read that the PX4Flow is no longer supported by AC developers, who are focusing on the the LidarLite.
For the time being I am ditching range finding and focusing on voice control, which I shall finally commence work on, this weekend.