I've heard many people recommend this lens for doc shooting. Out of curiosity, why do you feel it's a good lens for this purpose? Does it have to do with the OIS and versatility of focal lengths? Or is it more about the overall aesthetics of the lens?
Rough feeling, but with the 14-140 my AF100 feels a lot like my old HVX on full manual - a useful zoom range, easy to control, but with poor low light performance. Usually it's fine for any lit location (exterior day, stadium, lab, stage, studio), but inadequate if there isn't some significant light source. Focus is more selective, of course, even with the 14-140. GH2 + 14-140 just shrinks the visual side of that.
Unlit indoors or near dusk, I'll take one of the 4/3 midrange/midspeed zooms (14-54, 14-50, 12-60) any day over the 14-140.