I usually think of the two stops between µ4/3 and FF shared as 0.8 stops between µ4/3 and APS-C (Sony size sensor) and then 1.2 stops from APS-C to FF.
It depends on the aspect ratio of the final output.
If you compare at 4:3 aspect ratio, you lose part of the APS-C frame and the difference between Nikon/Sony and MFT is ~0.5 stops.
Comparing at 3:2 aspect ratio (cropping the 4:3 frame), the difference is ~0.9 stops (except for the multi-aspect ratio GH1 and GH2)
Comparing the Sony sensor at its native aspect ratio (3:2) to a MFT sensor at its native aspect ratio (4:3), the difference is ~0.7 stops.
For Canon APS-C versus MFT, the results are a bit different:
4:3 ~0.4 stops difference
native ~0.5 stops difference
3:2 ~0.7 stops difference (except for the multi-aspect ratio GH1 and GH2)
These are derived from log2 (sensor area X / sensor area Y)
You can use this calculator:
http://web2.0calc.com/
Of course those are just predicted differences based on similar sensor technology, which we know is not always the case.