Kurt, just dusted off my 5D and did a few tests in rubbish conditions (ISO 3200, Indoors, RAW, shooting a lightblub!)
I got 1 image previewed in 4 seconds. I could do a burst of 12 shots, but only after all 12 were written, did I get auto-preview show me the 12th image. However I could look at an image after about 6 seconds, and then cycle through the images as they are being written to CF.
I also shot with no CF card - and the preview was still 4 seconds.
Next I shot with ISO 100, and got the image after 3 seconds, inline with a smaller RAW files (10MB vs nearly 13MB).
Finally, shooting with ISO 100 and Jpeg fine, gave a 2.9MB file and preview after 2 seconds.
If you'd like me to run some other comparisons to your testing, then let me know the details.