I bought the GX7 because at the time it was the best M43 camera for me and even after the E-M1 I still would of bought the GX7. The GX7 definitely gets overlooked at my workplace because of the E-M5/10/1 and GM1 because of word of mouth, advertising and/or price/design.
I'm not sure, you mean the jittery bokeh? My 20 seems to be a bit cleaner than that, but I can still get a slight doubling effect like in this example. Maybe what you see is specific to his copy, or to version II, or just a situational combination of background, harsh light, etc.(these are from the Arizona desert, and the sunlight is quite harsh there), The Bokeh is much smoother in other examples he posted, so my guess is its situational.
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In my experience, this can happen with almost any lens. Basically just happens when the background is OoF, but just barely. For some reason, I think the 20mm just seems to find itself in these situation more often than other lenses. When it happens on the 25mm F1.4, it's worse. It just happens less often since that lens normally just has more bokeh in the first place. I think the only lens I haven't seen this happen on in M4/3 is the Nocticron. Doesn't bother me at all personally, though.