It's been a year since I disabled IBIS on my E-PM1 cause it is useless and more likely to cause blur than when it's off. Couple of days ago I decided to give it another try but this time with Anti-shock set to 1/8s. What a difference it makes! Used with Oly 45mm at 1/20s IBIS on, anti-shock 1/8s; 7 out of 10 images are tack sharp. with IBIS off, 0 out of 10 images are sharp at pixel level. With anti-shock off, IBIS on, none of the images are sharp and some are much worse than with IBIS on. I will continue to test it with other lenses as well but based on these preliminary results I believe that the tiny E-PM1 body doesn't handle shutter vibrations too well causing IBIS to overcompensate in most scenarios.