I have the GH2 and both the 14-45mm and 14-140mm. For stills I prefer the 14-45mm: its IQ is at least as good as that of the 14-140mm and it's much lighter. Especially when using the 14-140mm above 50mm the IQ degrades, especially in the corners and it's no match for the 45-200mm, so I don't see the point of using the 14-140mm for stills despite its obvious convenience of not having to switch between lenses. Also the 14-140mm's highlights tend to bleed into darker areas causing highlights to look somewhat unsharp.
BTW, I'm on my 2nd sample of the 14-140mm, both behave similarly. Will I keep mine? Yes, for video. Won't say anything about that, because I'm totally ignorant about video
