As people learn more and more about the properties of digital capture, and the cameras advance both in meg count and in-camera processing, the issues of dynamic range are lessening.
In my experience, all three of the new Canons are much improved in these areas. In addition, I have become more sensitive as to where to place the toe of my histogram readout on the LCD. Where I tended to slightly underexpose to assure preservation of the highlights, I now strive to " expose to the right " while taking care not to clip the highlights. When shooting RAW, I've found that you have more dynamic range latitude than slide film and a bit less than neg film ... so with experience you get to a point where very few if any shots are lost to blown highlights, and fewer and fewer shots suffer from crushed blacks that produce noise when lifted via the RAW developer or Shadow/Highlight tool in PSCS.
In fact, Proper technique employed in the RAW developer of PSCS allows amazing control of the dynamic range. When faced with crushed blacks, I lower the Contrast and use the Brighten slider as opposed to the Exposure slider, which I never use anymore.
Here is one of the first shots I took with the Canon 1DsMKII upon taking it out of the box in my studio. It is of a worker up a ladder fixing my skylight. The light was direct on his face and the room behind him was darkened. I don't know if it will show here on the web, but the darks contain plenty of detail while the front of his face is far from being blown. Subsequently, I have found that more of the L lens properties are apparent due to 16 megs of full frame capture. The true test will come in harsher sunlight. And I wish I had an adapter and some older Contax primes to run a test.
This shot was with the 1DsMKII @ ISO 800 (no noise!) using a Canon 180/3.5 handheld @ 1/50th (available light / no fill flash