Many people believe they absolutely need to upgrade from a DSLR to a dedicated CCD in order to produce world class deep sky images but if you take a look at this work by Ivan Eder I think you will agree they are some of the finest deep sky images taken by an amateur, and he uses modified Canon EOS's and his recent work is with a 5DmkII
His most recent work from Namibia is really breathtaking (the super seeing and perfect black skies probably helped too)
The Beauty of the Sky