Micro 4/3 sensors are extremely tiny and much, much smaller than APS-C sensors. f0.95 on a 35mm sensor gives you insanely shallow DOF and even on APS-C you're getting good isolation but on a m4/3 sensor the you don't get as much of the shallow effect. The OM-D + 75mm f1.8 lens for example produces some nice DOF but compared to say a 135 f2 on a D800 or 5D2/3 the bokeh will be harsher and more busy with more DOF.
M9's just eat up those kinds of lenses though you need a 4 or 8-stop ND just to shoot it wide open during the day

Oh, gotcha! I thought you meant that the 50 on the M9's FF would act like a 50 f/4 lens which kinda had me dumbfounded. 







