Marc
I have been shooting stitched panos for some time with the Canon 10D/20D/5D. I bought the ZD camera earlier this year in full knowledge of the speed limitations and knowing I'd still be using the 5D for the large stitching jobs. I wasn't wrong.
Some of my stitches are from only five or six frames and the ZD is fine for this - it's within the 11 shot buffer. On the other hand I do a fair number of multi-row stitches (maybe 20-30 frames) and these are not suitable for the ZD - at 10 seconds per shot after the 11 shot buffer is filled, you'd be there forever.
More often than not I bracket exposures - usually a bracket of three, but sometimes two or three sets of bracketed exposures i.e. six or nine shots.
An example. In this scenario of course the ZD is absolutely not usable. With these setups I occasionally hit the buffer on the 5D, so any MF rig will slow you down to some degree.
So at 50 or 100 ISO with exposures up to a few seconds the image quality is excellent and the dynamic range is certainly better than the 5D. For panos of up to eleven or so frames - including any bracketing - it is perfectly usable. But if you do very large stitch projects you'll need something faster, or stick to the 5D.
Regards
Frank