Hi Neil,
Yes the Sony panorama function is really useful, I use it when hill walking. A great innovation of your's to use it with the scope.
Another useful feature of software supplied with the compact Sony cameras, "PMB" or the recently upgraded "PlayMemories Home", is the ability to grab stills frames from video. You can run the video frame by frame and grab an image of choice. This isn't a screen grab, the software actually captures the frame as a jpeg.
Attached is an image grabbed from MP4 video using the PMB software. This was taken with a low end WX7 Sony compact and Celestron Ultima 80 ED scope.The moorhen was stretching it's wing and I grabbed this image at a suitable position.The image has not been manipulated only reduced in size for uploading.
It would be really interesting to see the quality of an image grabbed from high quality 1080p, 50 frame video taken with the RX100 on a high end scope. You should have had "PlayMemories Home" supplied with the RX100.
Maybe something you could try when you've got the time and give us your thoughts.