Found reference to this article over at mu-43. It explains the difference between Mode 1 continuous (best for video) and Mode 2 instantaneous (best for stills). Mode 3 is not discussed but is for horizontal panning (video or still) with correction only for vertical jitter. The IBIS in the Pens is different again (Mode 1 normal, Mode 2 horizontal panning, Mode 3 vertical panning) which is to be expected as it is in-body sensor adjustment. If you have any info on other systems please share.