It will be interesting if it's ever published/printed that the chip is exactly the same as Phase One/Hassi are using. However the range to 208K does not really surprise me.
1. Sony is currently tearing up the video market with the A7s announcement, only 12MP, but video up to 400K I believe, and so far the demo videos I have seen are impressive indeed on the new A7z, obviously Sony knows how to get to a higher ISO range.
2. Back in Feb, 2014, Alpa did a quick blog post on the IQ250, which showed the back in live view mode in total darkness. Basically the view view was able to pull the night scene into daylight, enough to allow easy focus, and there was not a lot of noise (like Nikon has in low light with live view on the D800).
Phase One may have chosen for internal reasons to govern the max ISO down in the IQ250 for now and they may push it in the future. If they are using the same chip as in the Pentax, then there is alot of more room possibly. However their ability to show a totally night scene in basically daytime, tells me the IQ250 may have the same reach.
You can read the Alpa blog here:
http://www.alpa.ch/en/news/2014/IQ250-review1At the very bottom of the blog article.
Paul