That's an interesting question.
The specification sheet for the P25 talks about a 12 f-stop range. Well, after a year of shooting with the P25 it certainly doesn't look like 12 f-stops to me! I haven't run any tests, but I'd very much doubt I'd be able to retain detail in both an area that metered 1/500s at f22 and an area that metered 1/4s at f4.0.
I'd guess the P25 gives a bit more dynamic range than a Canon 1Ds MkII, but no more than about a stop.
Unfortunately the ZD doesn't have the bit depth of the P25, consequently I wouldn't expect anything more in dynamic range terms than you'd get from a DSLR.
Still, I'd encourage any DSLR user to look at the ZD. IMO, in the real world rather than theorising from specification sheets, working with a larger sensor just makes quality so much easier to achieve. It takes the stress out of photography in the same way a V12 takes the stress out of motoring.