Digital Transitions, just posted this:
ISO Sweep: IQ250 - DT Blog
I can't speak to all 35mm DSLR's, however this is far superior to my D800e at even 3200. The file that DT has posted shows that the shadow area on the 6400 image is starting to fall apart, but the parts of the image that are in good light, are very good. 1600 and 3200 look very good.
It's sad that Phase currently is not offering a competitive upgrade/downgrade/whatever grade from the 260 to this back. Seeing this comparison, I could easily part with 10MP to have the range this chip has. Tech camera shifting is another issue, but that is something that needs to be tested more, and hopefully in an outdoor environment. I would like to see more tests with the 40mm Rod, and the 60mm Schneider.
Long term, it's clear Sony has quite a lead in chip technology. If they are working with Phase One on a full frame that handles tech shifts that would be excellent, however I have to wonder if the next chip will come from Dalsa. They don't have the same history with CMOS (at least in this market) so the question will be can they get the same amazing DR.
Kudos to Phase One, this is quite a back.