I saw the TX20 at the Sony store when I bought the RX100 last week, too bad it wasn't charge so I wasn't able to play with it. It looks exactly like the TX10 on the outside.
I'm not sure how much better the 20 is compared to the 10. I've had a TX10 for almost a year now. I am very pleased with its stills and video quality, BUT general operations can be slow and frustrating. Much of its functions are controlled by the touchscreen, and when the camera gets wet, the touch control can act erratically. General operations like playback mode is also kind of slow, which is pretty typical of Sony, but having to use the touch screen just to scroll the pictures when zooming makes it seem even slower. And worst of all, when you press the video start button, the actual recording doesn't start for about 5 seconds, so you will typically miss a few seconds' worth in the beginning.
Apart from that, it is lots of fun. I've taken many shots of the kids jumping into the pool with the 10fps burst. Awesome full HD 1080/60i underwater videos, love the smooth motion of 60fps. No it doesn't do 1080/60p, but even on my 5N, HX9V, and now RX100 I select 60i. Much easier to deal with on the computer.
SONY TX1O | HX9Vee | NEX-FiveN