I also saw an RX100 on display when I was in a BestBuy taking videos to compare the CX760 and GW77. Unfortunately, the way it was tethered prevented me from inserting an sd card to take comparative videos. What I did see was informative:
1. The zoom lever is much like that of the HX9v - clumsy, not easily controllable, and noisy. It only has one speed, and you really have to watch not going over to the digital zoom part, which highly degrades (from videos seen) and cannot be turned off.
2. The 3" LCD screen is 4:3 not 16:9. So in video mode, which is 16:9, you get black bars top and bottom - and the effective screen real estate for viewing in video mode is comparatively tiny and filled with icons. It is useful to see what exposure (f-stop and shutter) is being selected in auto, of course. But there is no indication of gain or iso, which is a key parameter.
3. The RX100 has trouble with reds in low light. The reds come out brownish red. I have seen this in comparative videos (the comparisons are to Sony camcorders).
This photo shows you what I am talking about - you see the truncated view in video, and how the screen shows the actual reds as brownish (the reds in the picture are accurate (you all have seen those Sandisk cards - they are red, not brown)). Interestingly, the RX100 chooses at f1.8 a shutter of 1/125th. The GW77 that I used to take the picture "chose" 1/60th of a second at the same aperture.