not much to add, except that i noticed fisheye much easier to use on m4/3 than on 3/2 cameras:
When i was shooting Nikon DX, i was quite happy with the angle of view of my 10-24mm Nikon, and was finding the 10-17mm Tokina fisheye usually too wide.
Now on m4/3 my 9-18mm often seems too narrow, whereas my pany 8mm fisheye does seem very OK, and with the Nauticam 3.5" mini-dome, the CFWA capabilities are just awesome!!! Not that i am an expect, but learning...
And the pictures look always crispier.
The 4/3 pictures being less "panoramic", composition with a fisheye gets easier i think.