Based on the video and the pictures above, we can all agree that higher FOM unit performs slightly better in low light environments. But, the difference is not big, even when comparing devises with such different FOM scale. To be hones, unless you compare units side-by-side, you would probably not even notice the difference. The difference in image quality is not as dramatic as comparing standard GEN2 to ECHO.
In addition, we have observed so far that the higher FOM ECHO units are usually a bit more spotty or have some other non-desirable attribute higher (EBI, Image Alignment). Why? Because if the unit goes above FOM 1800+, then firstly this unit is considered to be 4G. If during analysis some the attribute does not meet the 4G requirements, then it is classified as ECHO device.
In our case with the test-device with FOM 1979 – the image alignment is a bit too high for the unit to be considered for 4G. So, it was classified as ECHO instead.