I'm in the process of evaluating C1 v.8 for my Sony RX100 camera and I've run into a couple of problems.
1. The RX100 is a 20MPix camera -- the file dimensions in C1 output recipe summary are the same as outputs from LR5 and DxO Pro 9 (with its automatic lens distortion both off and on): 5472x3648 px. I assume that these are the same dimensions as the camera-created jpeg. However, when you output those files as jpegs or tiffs with C1 the dimensions seem to be uprezzed to 5731x3821 and also the output recipe summary now shows these uprezzed dimensions for the raw file. What's going on here? There is no such discrepancy for my Pentax K10D so I assume it's got something to do with some internal output recipe for the RX100 (?). Wouldn't such an uprezzing be detrimental to output sharpness of the file?
2. The lens corrections profile for the original RX100 has the Light Falloff slider permanently off and doesn't correct for the vignetting of the lens. You can access the slider only when you manually switch the profile to the RX100 Mk II lens (it's seemingly the same optics hardware-wise). Also it seems to undercorrect or overcorrect the distoritions at various focal lengths. That second profile makes the corrections similar to what you get from the in-camera jpeg, LR5 and DOP9, so this must be a profiling bug for RX100 Mk I.
3. The colours are wrong. When I shoot the ColorChecker Passport the red patch is orangish (there's too much yellow injected to red/pink tones, possibly to make skin tones more pleasing -- this might work with Canon, Nikon or Pentax reds but it doesn't work for Sony, at least not for my camera). So, the Caucasian skin rendition is sub-optimal and generally greens and yellows get too dense. You have to resort to the Color Editor to neutralize things and start optimizing the file only after you've corrected the defaults. Also, the shadows have magenta cast to them. The easiest way to correct for this second problem is changing the input shadow values of Red and Blue channels by 1 and 2 units respectively in the Levels tab -- you can make a preset for that -- but you shouldn't have to do that for a well-profiled camera.
4. A good point about C1: the LCC tool. The RX100 lens is prone to lens colour casting (esp. at the widest and at the longest focal lengths). Some of the magenta cast mentioned in point 3 can be exacerbated by this phenomenon. C1 is the only converter I know of that allows a semi-automatic way of correcting for that so kudos for that.
So, are there any other Sony RX100 C1 users in this forum and have you encountered similar problems? I've raised a support ticket with the colour issue but it didn't go anywhere and the case was closed with the conclusion that everything is within the norm. All in all, C1 makes me hate my RX100, which cannot be said of LR5 or PhotoNinja, which do very well with this camera. As it is I can't see myself ever reaching for this converter for this camera...