I'll chime in.
Recently I decided it was time to realize my dream of owning a proper camera and after much research decided on the G6. I needed something which provided excellent video quality without sacrificing the quality of stills too much and the G6 delivers on this. While I know the GX7 probably has marginally better image quality I don't really care since the G6 does everything I need it to in a neat package, and it's definitely no slouch for image quality either. I expect it will do me for 2-3 years at which point I'll probably upgrade to the GH6 or something.
The internal mic is indeed very competent and while I haven't used the GH2 the external mic input is surely comparable. The noise floor is very low. There does seem to be some sort of limiter preventing clipping too. I recently recorded a fairly loud live gig with a less than fantastic microphone and was pretty surprised at the complete lack of clipping. In the past I've used a D5100 for video and the mic input on that was incredibly noisy to the point that it was unusable. The G6 is not like that.
I also purchased an RJ speed booster and some old M42 lenses. With the speed booster my SMC 50mm 1.4 becomes a 71mm 1.0 which is pretty damn good for $30 or so. There probably isn't any image quality degradation but I don't know since I haven't used the lenses with a dumb adapter. It looks pretty damn good to me.
