Just to follow on from what Gary mentions...
The ST2kXCM is a very capable camera. The one shot colour certainly takes much less work in producing "pretty pictures". Though one shot colour CCD cameras along with DSLR's will not achieve the same quality output of a mono CCD camera equipped with colour filters. This isn't a debatable point. You only need to look around to see what the "pros" are using to see this trend. However, Mono CCD imaging with filters isn't for everyone. It does take a considerable effort to produce a good image compared to a one shot colour.
Other things to note;
- You'll still need to colour balance your images with a one shot colour camera. This is unavoidable. The workload is not as simple as many believe. You'll probably end up splitting out the individual R,G,B channels so you can manually work on them.
- In some cases exposure times with the one shot colour need to be longer than that of a mono camera due to the reduced QE. Though many one shot colour CCD chips have improved QE that are close or equal to mono chips nowadays.
- Regardless of the camera type, you'll still have battles dealing with light pollution and its associated gradients it will produce on your images. Mono does give you the edge if you want to use narrowband filters, though these can also be used with one shot colour cameras (but are less effective).
- Something that I didn't think of which was mentioned in an SBIG post on one shot colour cameras; "There are problems with colour artefacts, because in anti-blooming versions, the individual colours start to hit the ABG, at different points. So if you image a 'blue' star, and approach the ABG, the blue colour gets attenuated relative to the other colours, resulting in great problems with colour balance across the image."
- "There is also an artificial 'shift' induced by the positions of the different colour pixels, which results in displacement between the colours, as you start to approach being undersampled." Neither of these two issues occur using a mono camera with filters.
The one shot colour camera is certain a great step up from the DSLR and along with DSLR's, both have their uses in this hobby. It comes back to your goals. If you're in this hobby to have fun and capture a few pics, then the one shot colour will do the task nicely. If the price is right for the ST2kXCM - go for it. You can always sell and upgrade to a mono later down the track as your experience increases.