There's so much info on astro-photography that it's making my head spin

so I wonder if I can get some general advice on equipment with the goal of getting good high resolution DSO images in mind.
For example, if I have a good 4" APO refractor mounted on say a EQ6 mount and use some form of autoguiding is it possible to say what ccd camera (any make) would better a modified
Canon EOS 450D / Digital Rebel XSi DSLR?
Reason I ask is that I often read that to get the best images a ccd camera is the only way to go rather than a DSLR. That's obviously true with the mega dollar high end stuff but is it possible to say in what areas the above Canon DSLR would match say the QHY8 or the Orion StarShoot Deep Space Pro CCD camera's or are there too many other variants to consider?
Tim