Richard, it might help you if you decide on some targets that you’d like to go after, and go from there.
For large, sprawling nebulae, you might want the larger chip size, but for galaxy chasing the a small sensor with tiny pixels might be a more appropriate tool for the job (besides a larger scope!)
Hint: if you look in the imaging forum, some of the “old faithful” are joining the CMOS party. Not that there’s anything wrong with some of last gen CCDs, they’re just more expensive and not inherently superior to a good CMOS sensor...
And for your quoted budget, you can have a full frame DSLR _and_ a cooler CMOS camera
