This discussion always focuses on OSC versus Mono. But is this the only, let alone the right question/comparison? Many of us use DSLRs because of convenience, ease of use, reliability, cost and because they provide surprisingly rewarding results in the time available to us, especially considering astrophotography is not what they're designed for.
However, DSLRs fall down because of noise. A cooled OSC performs better in this regard. So the question might be: should the DSLR user move up to an OSC as a better way to do the sort of astrophotography they are already doing?