Originally Posted by
fanger
Another thing is that for a given format size and f stop, it is easier to achieve shallow depth of field (bokeh) on the larger sensors. 4/3 and smaller sensors don't have as many lens options capable of achieving the same bokeh possible on the larger formats.
That sword cuts both ways though. A smaller sensor can offer a significant exposure advantage when large DOF is desired.
They are (finally) addressing the fast lens options. Olympus just came out with 12/2.0 and 45/1.8 lenses. Panasonic/Leica just released a 25/1.4, and Panasonic has the pancake 20/1.7. Voigtlander has had a 25/0.95 out for a while. Sadly, no telephotos yet, but Panasonic has shown prototypes of upcoming "bright zooms" (Double all focal lengths for FF equivalent)