At the moment, there's really only two cameras I'd look at changing from my DMK21AU04 to:
- Lumenera Skynyx 2-0
- Point Grey Research Grasshopper
Last time I spoke with Anthony about this, he put me onto the grasshopper as he said he'll be upgrading to this camera shortly.
http://www.ptgrey.com/products/grass..._datasheet.pdf
The leftmost one, GRAS-03K2M/C.
You're also right, that any of these cameras will be suitable as an autoguider.
For planetary, you really don't want any more than 640x480 because you want the fast framerate. What focal length will you be imaging at?
Even Jupiter at opposition fits in the 640x480 px field of view at about 13-14mm focal length, and that's with the smaller pixel size of the DMK. With the lumemera and pt grey cameras, their pixel size is a bit bigger (7.4 microns) so the image scale is a bit smaller.
Don't forget the filter wheel and filters, too. What filters will you get?