As a known Contax /Phase user, I hesitate to show these, but it seemed instructive. I have been a great fan of the P25 and really never pushed to 100%, and always stay at 50-100 ISO.
However, I just tested the P45 vs p25 (I need to send it back, but thought I would check WB exposure etc with same camera and lens - here, strangely the 35mm)
What struck me is that there seems to be much more than 20% linear improvement, likely due to the fact that images are , after all, 2-d. But as some have commented that have the P45, it is a bigger jump from the SLRs than the P25. Here that is obvious. Also, noise was a real surprise (this was outside bright sun on a white object with sharp shadows. The p45 show real promise that the 45+ will handle 800, which I had doubted.
And I know, hardly scientific, the P25 is about 1/2 stop overexposed (but the P45 shot blew the highlights on the right as well)
Have others seen this? or was this just a peculiar situation? I keep my fingers crossed that this improvement carries through. Michael seems to have thought so, but then my middle name is 'doubt' :-)
One more thing. I certainly don't see the lens as a limit here, though it is a little soft at the edges even stopped down. I'm sure the Schneider or Rodenstack would have more detail, but this seems pretty good.
BTW I know it is a minor point, but the new Phase backs with the Value added(basically the extended warranty) also come with a fantastic case, aluminum, configurable not only for the back, butalso for the camera and a couple of lenses. A great bonus, esp with air travel being such a burden now. (can ship ahead, carry on etc.)